Long-term monitoring of SARS-CoV-2 seroprevalence and variants in Ethiopia provides prediction for immunity and cross-immunity.

Under-reporting of COVID-19 and the limited information about circulating SARS-CoV-2 variants remain major challenges for many African countries. We analyzed SARS-CoV-2 infection dynamics in Addis Ababa and Jimma, Ethiopia, focusing on reinfection, immunity, and vaccination effects. We conducted an antibody serology study spanning August 2020 to July 2022 with five rounds of data collection across a population of 4723, sequenced PCR-test positive samples, used available test positivity rates, and constructed two mathematical models integrating this data. A multivariant model explores variant dynamics identifying wildtype, alpha, delta, and omicron BA.4/5 as key variants in the study population, and cross-immunity between variants, revealing risk reductions between 24% and 69%. An antibody-level model predicts slow decay leading to sustained high antibody levels. Retrospectively, increased early vaccination might have substantially reduced infections during the delta and omicron waves in the considered group of individuals, though further vaccination now seems less impactful.

How does the SARS-CoV-2 reinfection rate change over time? The global evidence from systematic review and meta-analysis.

BACKGROUND: There is a significant increase in the number of SARS-CoV-2 reinfection reports in various countries. However, the trend of reinfection rate over time is not clear. METHODS: We searched PubMed, Web of Science, Medline, Embase, Cochrane Central Register of Controlled Trials, China National Knowledge Infrastructure, and Wanfang for cohort studies, case-control studies, and cross-sectional studies up to March 16, 2023, to conduct a meta-analysis of global SARS-CoV-2 reinfection rate. Subgroup analyses were performed for age, country, study type, and study population, and time-varying reinfection rates of SARS-CoV-2 were estimated using meta-regression. The risk of bias was assessed using the Newcastle-Ottawa Scale and the Joanna Briggs Institute critical appraisal tool. RESULT: A total of 55 studies involving 111,846 cases of SARS-CoV-2 reinfection were included. The pooled SARS-CoV-2 reinfection rate was 0.94% (95% CI: 0.65 -1.35%). In the subgroup analyses, there were statistically significant differences in the pooled reinfection rates by reinfection variant, and study type (P < 0.05). Based on meta-regression, the reinfection rate fluctuated with time. CONCLUSION: Meta-regression analysis found that the overall reinfection rate increased and then decreased over time, followed by a period of plateauing and then a trend of increasing and then decreasing, but the peak of the second wave of reinfection rate was lower than the first wave. SARS-CoV-2 is at risk of reinfection and the Omicron variant has a higher reinfection rate than other currently known variants. The results of this study could help guide public health measures and vaccination strategies in response to the Coronavirus Disease 2019 (COVID-19) pandemic.

The symptoms and interval of Omicron SARS-CoV-2 reinfection among healthcare workers in a hospital of Southern China: a cross-sectional study.

BACKGROUND: The prevalence and distinction between first Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and reinfection with the Omicron variant among healthcare workers (HCWs) remain unclear. METHODS: A cross-sectional study was conducted at a hospital in Southern China. The study included 262 HCWs who were infected with SARS-CoV-2 between April and June 2023, with 101 cases of first infection and 161 ones of reinfection. Student's t-test, Analysis of Variance (ANOVA), and Mann-Whitney U tests were used based on the distribution of quantitative variables. Pearson's chi-square and Fisher's exact tests were used based on the expected frequencies of categorical variables. RESULTS: The reinfection rate among HCWs was 11.5% (161/1406). The majority of the infected HCWs were female (212/262, 80.9%, first infection vs. reinfection: 76.2% vs. 83.9%). The nursing staff, had the highest percentage of SARS-CoV-2 infection (42.0%), especially of its reinfection (47.8%). Out of the 262 infected individuals, 257 had received SARS-CoV-2 vaccination, primarily inactivated vaccines (243/257, 91.1%). The first infection group, which received four doses (24, 23.8%), was significantly higher than that in the reinfection group (6, 3.7%) (P < 0.001). The proportion of asymptomatic infections among HCWs in the two groups was 1.0% and 1.2%. The main symptoms during the first infection and reinfection were fever (83.2% and 50.9%) and sore throat (78.2% and 77.0%). There were significant differences in the prevalence of fever (83.2% vs. 50.9%), rhinorrhea (45.5% vs. 60.9%) and myalgia (56.4% vs. 37.9%) between the first infection and reinfection (P < 0.05). The average interval for SARS-CoV-2 reinfection was 149.9 (range: 114-182, SD = 11.9) days. Notably, physicians had the shortest average interval of 142.8 (8.8) days, while management and administrative staff had the longest average interval of 153.8 (13.5) days. CONCLUSIONS: Although the symptoms of HCWs during reinfection with SARS-CoV-2 were milder, the high reinfection rate and short interval between infections indicate the need to enhance monitoring and protective measures for HCWs during the epidemic.

Comparative outcomes of SARS-CoV-2 primary and reinfection in older adult patients.

Background: The outcomes of older adult people acquiring SARS-CoV-2 reinfection was unclear. This study aimed to compare the outcomes of older adult patients with COVID-19 reinfection and those with primary infection. Methods: This retrospective cohort study used electronic medical records from the TriNetX Research Network. Older adult patients (aged ≥65 years) with COVID-19 between January 1, 2022, and December 31, 2022, were included in the study. The patients were subsequently categorized into reinfection or primary infection groups, according to whether they manifested two distinct COVID-19 episodes with an intervening period of more than 90 days. Propensity score matching was performed for covariate adjustment between the reinfection and primary infection groups. The primary outcome was a composite outcome, including emergency department visits, hospitalization, intensive care unit admission, mechanical ventilation use, and mortality, following primary infection and reinfection. Results: After matching, 31,899 patients were identified in both the reinfection and primary infection groups. The risk of primary composite outcomes was 7.15% (n = 2,281) in the reinfection group and 7.53% (n = 2,403) in the primary infection group. No significant difference in the primary outcome was observed between groups (HR, 0.96; 95% CI, 0.91 to 1.02, p = 0.17). In addition, there was no significant differences between the reinfection and primary infection groups in terms of emergency department visit (HR, 1.03; 95% CI, 0.95 to 1.11, p = 0.49), all-cause hospitalization (HR, 0.94; 95% CI, 0.86 to 1.02, p = 0.14), intensive care unit admission (HR, 0.92; 95% CI, 0.67 to 1.28, p = 0.62), mechanical ventilation use (HR,1.35 95% CI, 0.69 to 2.64 p = 0.38), and all-cause mortality (HR, 0.94; 95% CI, 0.74 to 1.20, p = 0.62). Conclusion: There were no significant differences in clinical outcomes between older adult patients with COVID-19 reinfection and those with primary infection.

Breakthrough infection and reinfection in patients with mpox.

Recently, patients with Mpox breakthrough infection or reinfection were constantly reported. However, the induction, risk factors, and important clinical symptoms of breakthrough infection and reinfection of Mpox virus (MPXV), as well as the factors affecting the effectiveness of Mpox vaccine are not characterized. Herein, a literature review was preformed to summarize the risk factors and important clinical symptoms of patients with Mpox breakthrough infection or reinfection, as well as the factors affecting the effectiveness of smallpox vaccine against Mpox. Results showed that MSM sexual behavior, condomless sexual behavior, multiple sexual partners, close contact, HIV infection, and the presence of comorbidity are important risk factors for Mpox breakthrough infection and reinfection. Genital ulcers, proctitis, and lymphadenopathy are the important clinical symptoms of Mpox breakthrough infection and reinfection. The effectiveness of emergent vaccination of smallpox vaccine for post-exposure of MPXV is associated with smallpox vaccination history, interval between exposure and vaccination, and history of HIV infection. This review provides a better understanding for the risk factors and important clinical symptoms of Mpox breakthrough infection and reinfection, as well as the formulation of Mpox vaccine vaccination strategies.

Risk of SARS-CoV-2 reinfection during multiple Omicron variant waves in the UK general population.

SARS-CoV-2 reinfections increased substantially after Omicron variants emerged. Large-scale community-based comparisons across multiple Omicron waves of reinfection characteristics, risk factors, and protection afforded by previous infection and vaccination, are limited. Here we studied ~45,000 reinfections from the UK's national COVID-19 Infection Survey and quantified the risk of reinfection in multiple waves, including those driven by BA.1, BA.2, BA.4/5, and BQ.1/CH.1.1/XBB.1.5 variants. Reinfections were associated with lower viral load and lower percentages of self-reporting symptoms compared with first infections. Across multiple Omicron waves, estimated protection against reinfection was significantly higher in those previously infected with more recent than earlier variants, even at the same time from previous infection. Estimated protection against Omicron reinfections decreased over time from the most recent infection if this was the previous or penultimate variant (generally within the preceding year). Those 14-180 days after receiving their most recent vaccination had a lower risk of reinfection than those >180 days from their most recent vaccination. Reinfection risk was independently higher in those aged 30-45 years, and with either low or high viral load in their most recent previous infection. Overall, the risk of Omicron reinfection is high, but with lower severity than first infections; both viral evolution and waning immunity are independently associated with reinfection.

SARS-CoV-2 reinfection with Omicron variant in Shaanxi Province, China: December 2022 to February 2023.

BACKGROUND: Prior to December 2022, there were no reports of reinfection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Shaanxi province, China. Since then, China has refined its strategy in response to coronaviruses. The purpose of this study was to determine the incidence of SARS-CoV-2 reinfections and its contributing factors, as well as to compare clinical characteristics between first and second episodes of infection in Shaanxi Province, China between December 2022 and February 2023. METHODS: We conducted a cross-sectional study using an epidemiological survey system and electronic questionnaires to investigate the incidence of SARS-CoV-2 reinfection among previously infected individuals during the epidemic wave owing to the Omicron variant that began in December 2022. A logistic regression model was used to determine those factors influencing SARS-CoV-2 reinfections. RESULTS: According to the virus variant that caused the first infection, the rate of reinfection for the Omicron variants was 1.28%, 1.96%, and 5.92% at 2-3 months, 4-5 months, and 7-9 months after the primary infection, respectively. The rate of reinfection for the Delta variants was 25.10% 11-12 months after the primary infection. Females, adults between 18 and 38 years and being a medical worker were associated with an increased risk of reinfection. Fever, cough, sore throat and fatigue were the four most common clinical symptoms during both first and second COVID-19 infections. CONCLUSIONS: In our study, the rate of SARS-CoV-2 reinfection increased over time during epidemic waves predominantly involving the Omicron variant in Shaanxi province, China. Large-scale infections are less likely in subsequent Omicron epidemic waves. Nevertheless, it is essential to continuously monitor cases of infection as well as continue surveillance for emerging SARS-CoV-2 variants.

COVID-19 Reinfection Has Better Outcomes Than the First Infection in Solid Organ Transplant Recipients.

BACKGROUND: Solid organ transplant recipients face an increased risk of severe coronavirus disease 2019 (COVID-19) and are vulnerable to repeat severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. In nonimmunocompromised individuals, SARS-CoV-2 reinfections are milder likely because of cross-protective immunity. We sought to determine whether SARS-CoV-2 reinfection exhibits milder manifestations than primary infection in transplant recipients. METHODS: Using a large, prospective cohort of adult transplant patients with COVID-19, we identified patients with SARS-CoV-2 reinfections. We performed a 1:1 nearest neighbor propensity score matching to control potential confounders, including the COVID-19 variant. We compared outcomes including oxygen requirement, hospitalization, and intensive care unit admission within 30 d after diagnosis between patients with reinfection and those with the first episode of COVID-19. RESULTS: Between 2020 and 2023, 103 reinfections were identified in a cohort of 1869 transplant recipients infected with SARS-CoV-2 (incidence of 2.7% per year). These included 50 kidney (48.5%), 27 lung (26.2%), 7 heart (6.8%), 6 liver (5.8%), and 13 multiorgan (12.6%) transplants. The median age was 54.5 y (interquartile range [IQR], 40.5-65.5) and the median time from transplant to first infection was 6.6 y (IQR, 2.8-11.2). The time between the primary COVID-19 and reinfection was 326 d (IQR, 226-434). Three doses or more of SARS-CoV-2 vaccine are received by 87.4% of patients. After propensity score matching, reinfections were associated with significantly lower hospitalization (5.8% versus 19.4%; risk ratio, 0.3; 95% CI, 0.12-0.71) and oxygen requirement (3.9% versus 13.6%; risk ratio, 0.29; 95% CI, 0.10-0.84). In a within-patient analysis only in the reinfection group, the second infection was milder than the first (3.9% required oxygen versus 19.4%, P < 0.0001), and severe first COVID-19 was the only predictor of severe reinfection. CONCLUSIONS: Transplant recipients with COVID-19 reinfection present better outcomes than those with the first infection, providing clinical evidence for the development of cross-protective immunity.

Risk of SARS-CoV-2 Reinfection in Children Within the 12 Months Following Mild COVID-19: Insights From a Survey Study.

Understanding the correlation between immune response and protection from COVID-19 will play a pivotal role in predicting the effectiveness of vaccines in children. We studied SARS-CoV-2 reinfection risk in children 12 months post-mild COVID-19. Children under 5 years old exhibited lower reinfection risk than older infected or vaccinated siblings during 12 months postimmunization.

Impact on the time elapsed since SARS-CoV-2 infection, vaccination history, and number of doses, on protection against reinfection.

SARS-CoV-2 reinfections have been frequent, even among those vaccinated. The aim of this study is to know if hybrid immunity (infection + vaccination) is affected by the moment of vaccination and number of doses received. We conducted a retrospective study in 746 patients with a history of COVID-19 reinfection and recovered the dates of infection and reinfection and vaccination status (date and number of doses). To assess differences in the time to reinfection(tRI) between unvaccinated, vaccinated before 6 months, and later; and comparing one, two or three doses (incomplete, complete and booster regime) we performed the log-rank test of the cumulative incidence calculated as 1 minus the Kaplan-Meier estimator. Also, an adjusted Cox-regression was performed to evaluate the risk of reinfection in all groups. The tRI was significantly higher in those vaccinated vs. non-vaccinated (p < 0.001). However, an early incomplete regime protects similar time than not receiving a vaccine. Vaccination before 6 months after infection showed a lower tRI compared to those vaccinated later with the same regime (adj-p < 0.001). Actually, early vaccination with complete and booster regimes provided lower length of protection compared to vaccinating later with incomplete and complete regime, respectively. Vaccination with complete and booster regimes significantly increases the tRI (adj-p < 0.001). Vaccination increases the time it takes for a person to become reinfected with SARS-CoV-2. Increasing the time from infection to vaccination increases the time in which a person could be reinfected and reduces the risk of reinfection, especially in complete and booster regimes. Those results emphasize the role of vaccines and boosters during the pandemic and can guide strategies on future vaccination policy.

Frequency and risk of SARS-CoV-2 reinfections in Norway: a nation-wide study, February 2020 to January 2022.

BACKGROUND: SARS-CoV-2 reinfection rates have been shown to vary depending on the circulating variant, vaccination status and background immunity, as well as the time interval used to identify reinfections. This study describes the frequency of SARS-CoV-2 reinfections in Norway using different time intervals and assesses potential factors that could impact the risk of reinfections during the different variant waves. METHODS: We used linked individual-level data from national registries to conduct a retrospective cohort study including all cases with a positive test for SARS-CoV-2 from February 2020 to January 2022. Time intervals of 30, 60, 90 or 180 days between positive tests were used to define potential reinfections. A multivariable Cox regression model was used to assess the risk of reinfection in terms of variants adjusting for vaccination status, demographic factors, and underlying comorbidities. RESULTS: The reinfection rate varied between 0.2%, 0.6% and 5.9% during the Alpha, Delta and early Omicron waves, respectively. In the multivariable model, younger age groups were associated with a higher risk of reinfection compared to older age groups, whereas vaccination was associated with protection against reinfection. Moreover, the risk of reinfection followed a pattern similar to risk of first infection. Individuals infected early in the pandemic had higher risk of reinfection than individuals infected in more recent waves. CONCLUSIONS: Reinfections increased markedly during the Omicron wave. Younger individuals, and primary infections during earlier waves were associated with an increased reinfection risk compared to primary infections during more recent waves, whereas vaccination was a protective factor. Our results highlight the importance of age and post infection waning immunity and are relevant when evaluating vaccination polices.

Risk factors and mortality of SARS-CoV-2 reinfection during the Omicron era in Taiwan: A nationwide population-based cohort study.

BACKGROUND: Prior to 2022, Taiwan had effectively contained the domestic COVID-19 epidemic. However, during 2022, the country encountered multiple large outbreaks of COVID-19, with patients experiencing their first or second infection (reinfection) were both predominantly caused by the Omicron variant. Data are lacking on the risk factors and mortality of COVID-19 reinfection in Omicron era. METHODS: In this retrospective population-based cohort study, we recruited COVID-19 patients with their first episode confirmed between April 1, 2022 and June 11, 2022. A reinfection patient was defined as an individual who infected again by SARS-CoV-2 with an interval of more than 90 days. Demographic characteristics, severity of underlying diseases, and vaccination status were adjusted to identify risk factors for reinfection and to further evaluate the hazard of all-cause mortality within 30 days between reinfection and non-reinfection patients. RESULTS: There were 28,588 reinfection patients matched with 142,940 non-reinfection patients included in this study. We found that being female, younger in age, having more severe underlying diseases, and not being fully vaccinated against COVID-19 were risk factors for reinfection. After adjusting for confounding factors, reinfection patients were at a significantly higher risk of all-cause mortality within 30 days (aHR = 4.29, 95% CI: 3.00-6.12, p < 0.001) comparing with non-reinfection patients. CONCLUSION: During the SARS-CoV-2 Omicron era, reinfection patients were observed to have an increased risk of all-cause mortality. To reduce the disease burden and minimize the risk of reinfection, it is crucial for vulnerable patients to receive full vaccination and adhere to recommended precautions.

Antibody response and risk of reinfection over 2 years among the patients with first wave of COVID-19.

OBJECTIVES: To describe the dynamics and factors related to natural and hybrid humoral response against the SARS-CoV-2 and risk of reinfection among first-wave patients. METHODS: A prospective longitudinal study with periodic serological follow-up after acute onset of all recovered patients with SARS-CoV-2 infection cared in Udine Hospital (March-May 2020). Nucleocapsid (N) protein and spike receptor-binding domain (S-RBD) antibody tests were used to distinguish natural and vaccine-induced response. RESULTS: Overall, 153 patients (66 men, mean age 56 years) were followed for a median of 27.3 (interquartile range 26.9-27.8) months. Seroreversion was 98.5% (95% CI: 96.8-99.4) for SARS-CoV-2-N IgM at 1 year and 57.4% (95% CI: 51.5-63.5) for SARS-CoV-2-N IgG at 2 years. Initial serological response (hazard ratio [HR]: 0.99, 95% CI: 0.99-0.99, p 0.002 for IgM and HR: 0.97, 95% CI: 0.97-0.98, p < 0.001 for IgG) and severity of acute infection (HR: 0.62, 95% CI: 0.39-0.96, p 0.033 for IgM and HR: 0.60, 95% CI: 0.37-0.99, p < 0.001 for IgG) were independently associated with persistent SARS-CoV-2-N IgM/IgG response. Older age and smoker status were associated with long-term SARS-CoV-2-N IgM and SARS-CoV-2-N IgG, respectively (HR: 0.75, 95% CI: 0.57-0.98, p 0.038; HR: 1.77, 95% CI: 1.19-2.61, p 0.004 respectively). All patients maintained SARS-CoV-2-S-RBD IgG response at 24-month follow-up. Reinfections occurred in 25 of 153 (16.3%) patients, mostly during the omicron circulation. Reinfection rates did not differ significantly between SARS-CoV-2-N IgG seronegative and seropositive patients (14/89, 15.7% vs. 10/62, 16.1%, p 0.947). Unvaccinated patients had higher risk of reinfection (4/7, 57.1% vs. vaccinated 21/146, 14.4%, p 0.014). DISCUSSION: First-wave patients had durable natural humoral immunity in 40% and anti-S-RBD response in 100% up to 2 years after infection. Natural humoral response alone was not protective against reinfections with omicron SARS-CoV-2 variants, whereas vaccination was effective to reduce the risk of a new infection.

Contaminação pelo Covid-19 em profissionais de hospital de referência no Pará / Contamination by Covid-19 in professionals of a reference hospital in Para's state / Contaminación por Covid-19 en profesionales de un hospital de referencia del estado de Pará

A pandemia do novo coronavírus colocou em alerta os sistemas de saúde, estabelecendo sentimentos de instabilidade e de medo. O trabalho é e importante pilar para o traçado de políticas públicas. Objetivo: analisar a contaminação pelo COVID-19 em profissionais de hospital de referência no Pará. Metodologia: Trata-se de estudo retrospectivo, quantitativo, observacional, com aplicação de série temporal no período de março de 2020 a março de 2022. Foram incluídos todos os servidores atuantes durante a pandemia, que apresentaram atestados médicos com diagnóstico de COVID, e/ou testagem positiva, ou atestados por suspeita de contaminação. O perfil de servidores foi analisado, explorando as variáveis sexo, idade, convivência ou não com parceiros, grau de escolaridade, cargo e setor; juntamente com a incidência de casos confirmados e incidência total (suspeitos e confirmados). Resultados: O total de afastamentos do trabalho devido ao diagnóstico de COVID-19 foi de 1.420 casos, mais 839 casos suspeitos; sendo que 173 trabalhadores apresentaram reincidência. A incidência foi maior nos meses de maio de 2020, março de 2021 e janeiro de 2022. Houve predominância do sexo feminino e da categoria de enfermagem. Setores administrativos e financeiros apresentaram maior porcentagem de contaminados durante a pandemia (73,40%), proporcionalmente ao quantitativo de servidores atuantes na lotação. Entretanto, foram servidores da assistência direta ao paciente que apresentaram maior porcentagem de reinfecção. Conclusão: Foi possível visualizar três ondas na distribuição temporal dos casos de COVID-19, com destaque para elevação nos primeiros meses de 2022. O declínio no diagnóstico de casos novos no hospital estudado após dois anos de pandemia pode representar esforços individuais e coletivos em resistir às dificuldades da conjuntura. É importante observar o comportamento da pandemia em distintas regiões do Brasil para atualização de estratégias de enfrentamento como um todo.

The new coronavirus pandemic has put health systems on alert, establishing feelings of instability and fear. Working is an important pillar for the design of public policies. Objective: to analyze the contamination by COVID-19 in professionals of a reference hospital in Para's State. Methodology: This is a retrospective, quantitative, observational study, with the application of a time series from March 2020 to March 2022. All civil servants working during the pandemic, who presented medical certificates with a diagnosis of COVID, and/or or positive test, or attestations for suspected contamination. The servants' profile was analyzed, exploring the variables sex, age, living or not with partners, education level, position and sector; along with the incidence of confirmed cases and total incidence (suspected and confirmed). Results: The total number of absences from work due to the diagnosis of COVID-19 was 1,420 cases, plus 839 suspected cases; 173 workers presented recurrence. The incidence was higher in the months of May 2020, March 2021 and January 2022. There was a predominance of females and the nursing category. Administrative and financial sectors had a higher percentage of people infected during the pandemic (73.40%), proportionally to the number of servers working in the capacity. However, it was direct patient care workers who had the highest percentage of reinfection. Conclusion: It was possible to visualize three waves in the temporal distribution of COVID-19 cases, with emphasis on an increase in the first months of 2022. The decline in the diagnosis of new cases in the hospital studied after two years of the pandemic may represent individual and collective efforts to resist to the difficulties of the situation. It is important to observe the behavior of the pandemic in different regions of Brazil to update coping strategies in a general scenery.

La nueva pandemia de coronavirus ha puesto en alerta a los sistemas de salud, estableciendo sentimientos de inestabilidad y miedo. El trabajo es un pilar importante para el diseño de políticas públicas. Objetivo: analizar la contaminación por COVID-19 en profesionales de un hospital de referencia en el Estado de Pará. Metodología: Se trata de un estudio retrospectivo, cuantitativo, observacional, con la aplicación de una serie de tiempo de marzo de 2020 a marzo de 2022. Todos los funcionarios que trabajaron durante la pandemia, que presentaron certificados médicos con diagnóstico de COVID, y/o o test positivo, o atestados por sospecha de contaminación. Se analizó el perfil de los funcionarios, explorando las variables sexo, edad, convivencia o no con la pareja, nivel de escolaridad, cargo y sector; junto con la incidencia de casos confirmados y la incidencia total (sospechosos y confirmados). Resultados: El número total de bajas laborales por diagnóstico de COVID-19 fue de 1.420 casos, más 839 casos sospechosos; 173 trabajadores presentaron recurrencia. La incidencia fue mayor en los meses de mayo de 2020, marzo de 2021 y enero de 2022. Hubo predominio del sexo femenino y de la categoría de enfermería. Los sectores administrativo y financiero presentaron mayor porcentaje de infectados durante la pandemia (73,40%), proporcionalmente al número de servidores que trabajaban en esa función. Sin embargo, fueron los trabajadores de atención directa al paciente los que presentaron el mayor porcentaje de reinfección. Conclusiones: Fue posible visualizar tres olas en la distribución temporal de los casos de COVID-19, destacándose un aumento en los primeros meses de 2022. La disminución en el diagnóstico de nuevos casos en el hospital estudiado después de dos años de pandemia puede representar esfuerzos individuales y colectivos para resistir a las dificultades de la situación. Es importante observar el comportamiento de la pandemia en diferentes regiones de Brasil para actualizar las estrategias de afrontamiento en un escenario general.

SARS-CoV-2 immune response and reinfection in vaccinated Maya and mestizo in Southeast of Mexico.

Immune response to pathogens, including coronaviruses, is influenced by HLA haplotypes. 1,2. Maya ethnic group is predominant in Yucatan peninsula, this Amerindian group present allele frequency  HLA-G*01:01:02, HLA-G*01:01:01, HLA-G*01:04:01, HLA-A*68  not found in another Amerindians.3-5 Immune response to SARS-CoV-2 vaccination and reinfection particularly after Omicron variant appeared was explored in 118 vaccinated subjects with complete two shots immunization in Maya ascendant and mestizo no-Maya. 1172 epidemiological survey applied to university staff in Campeche, Mexico to evaluate reinfection, co-morbidities, variant virus, disease severity, aftermaths, clinical outcomes, age, sex, ethnicity, and vaccination shots. Multiple logistic regression, correspondence analysis, and association tests were used to analysis data.   Sixteen percent  of vaccinated subjects became seronegative after 11 months. We found that vaccinated Maya subjects respond with higher IgG immune response compared to no-Maya subjects, similarly women respond with higher IgG response than men (p<0.05). During an eleven-month period and after two vaccination shots, 7% of the vaccinated subjects reported a confirmed positive infection, and after the third vaccine shot a higher IgG immune response than two vaccination shots or natural infection was detected. However, we observed 23.7% reinfection in people after the third shot. This data represents almost three times  the reinfection rate reported when compared to  previous third vaccine shots. The increase of reinfection in vaccinated subjects was associated with circulation of Omicron variant by 71.5%. Others have reported  reinfection of 40% and vaccine effectiveness of 60% during Omicron dominance.6 To understand COVID-19 severity after reinfection in vaccinated subjects and the associated variables, we carried out a multiple logistic regression, and found a strong association between less severe symptoms with Alfa and Omicron variants (B 5.3; Error 0.39; Wald 0.00; Significance 0.00; OR201).  However, subjects with severe symptoms and or hospitalization correspondent to individuals with multiplex comorbidities and  Gamma SARS-CoV-2 variants (B 5.06; Error 0.97; Wald 26.8; Significance 0.00; OR 158). A follow-up survey of COVID-19 recovered patients experienced diverse digestive, respiratory, cardiac, neurological, or joints involvement sequelae. We looked for SARS-CoV-2 variant and COVID-19 sequelae in a correspondence analysis. Our data suggest that Beta and Delta variants are associated with respiratory and digestive symptoms, whereas Omicron was more closely associated with joints and digestive symptoms, and finally the Gamma variant displayed wider and more diverse symptoms. Our results suggest that genetic background and gender influence IgG response to SARS-CoV-2 vaccine, and  Maya ascendant has higher immune IgG response to vaccine than mestizos. Reinfection in our population studied fluctuate from 7% to 23.7% nevertheless is higher if Omicron variant is involved, but symptoms are less severe and more closely associated with joints and digestive symptoms.

Risk Factors Contributing to Reinfection by SARS-CoV-2: A Systematic Review.

This article aims to systematize the evidence regarding risk factors associated with COVID-19 reinfection. We conducted a systematic review of all the scientific publications available until August 2022. To ensure the inclusion of the most recent and relevant information, we searched the PubMed and Scopus databases. Thirty studies were reviewed, with a significant proportion being analytical observational case-control and cohort studies. Upon qualitative analysis of the available evidence, it appears that the probability of reinfection is higher for individuals who are not fully immunized when exposed to a new variant, females, those with pre-existing chronic diseases, individuals aged over 60, and those who have previously experienced severe symptoms of the disease or are immunocompromised. In conclusion, further analytical observational case-control studies are necessary to gain a better understanding of the risk factors associated with SARS-CoV-2 (COVID-19) reinfection.

Reinfection rates, change in antibody titers and adverse events after COVID-19 vaccination among patients previously infected with COVID-19 in Metro Manila, Philippines: a secondary analysis of a completed cohort study.

BACKGROUND: Variation in immune response to COVID-19 vaccines is observed among different ethnicities. We aimed to describe the reinfection rates, change in antibody titers, and adverse events among Filipinos. METHODS: This is a secondary analysis of a cohort study of 307 participants within one year of having COVID-19 infection. We measured COVID-19 antibody levels at pre-determined timepoints (Days 21, 90, 180, 270, and 360 from initial infection). We monitored for COVID-19 symptoms and obtained details on COVID-19 vaccination. An adjudication committee classified the participants as probable, possible, or unlikely COVID-19 reinfection. We determined the probable reinfection rate, adverse events, and the geometric mean titer (GMT) ratio of pre- and post-vaccination antibody levels according to type and brand of COVID-19 vaccine. RESULTS: At the end of the follow-up period, 287 (93.5%) out of 307 study participants were fully vaccinated, 1 was partially vaccinated (0.3%), and 19 were unvaccinated (6.2%). Among the fully vaccinated participants, those given mRNA vaccines had the lowest reinfection rate (19.2 cases/100 person-years, 95% CI 9.6, 38.4), followed by viral vector vaccines (29.8 cases/100 person-years, 95% CI 16.9, 52.4). We observed the highest reinfection rate among those given inactivated virus vaccines (32.7 cases/100 person-years, 95% CI 23.6, 45.3). The reinfection rate was 8.6 cases/100 person-years (95% CI 4.1, 17.9) for unvaccinated participants and 3.6 cases/100 person-years (95% CI 0.5, 25.3) for partially vaccinated participants. We observed the largest rise in antibody titers among those given mRNA vaccines (GMT ratio 288.5), and the smallest rise among those given inactivated virus vaccines (GMT ratio 16.7). We observed the highest percentage of adverse events following immunization with viral vector vaccines (63.8%), followed by mRNA vaccines (62.7%), and the lowest for inactivated virus vaccines (34.7%). No serious adverse events were reported. CONCLUSION: Vaccinees given the mRNA vaccines had the lowest reinfection rate and the highest rise in antibody titers. Vaccinees given inactivated virus vaccines had the highest reinfection rate, smallest rise in antibody titers, and lowest percentage of adverse events. The small sample size and imbalanced distribution of the type of vaccines received limits the external generalizability of our results. STUDY REGISTRATION: The cohort study was registered at the Philippine Health Research Registry on December 14, 2020 (PHRR201214-003199).

Evaluation of SARS-CoV-2-Positive Patients with Suspected Reinfection.

The aim of this study was to investigate the reinfection rates and characteristics of SARS-CoV-2 in individuals with SARS-CoV-2 RNA present in their clinical specimens for COVID-19. Our data from the COVID-19 Laboratory of Istanbul University were analyzed for 27,240 cases between 27 March 2020 to 8 February 2022. Demographic characteristics, vaccination statuses, comorbidities, and laboratory findings were evaluated in cases with suspected reinfection, as determined by the presence of SARS-CoV-2 RNA at a rate of 0.3% in clinical specimens. When comparing laboratory values, leukocyte counts were lower in the second and third infections compared with the first infection (p = 0.035), and neutrophil counts were lower in the second infection (p = 0.009). Symptoms varied, with coughing being common in the first infection and malaise being common in subsequent infections. These results suggest that it is important to continue to monitor reinfection rates and develop strategies to prevent reinfection. Our results also suggest that clinicians should be aware of the possibility of reinfection and monitor patients for recurrent symptoms.

Incidence and outcome of SARS-CoV-2 reinfection in the pre-Omicron era: A global systematic review and meta-analysis.

Background: With the emergence of new variants and sub-lineages of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), reinfections can significantly impact herd immunity, vaccination policies, and decisions on other public health measures. We conducted a systematic review and meta-analysis to synthesise the global evidence on SARS-CoV-2 reinfections in the pre-Omicron era. Methods: We searched five global databases (MEDLINE, Embase, CINAHL Plus, Global Health, WHO COVID-19) on 12 May 2022 and 28 July 2023 and three Chinese databases (CNKI, Wanfang, CQvip) on 16 October 2022 for articles reporting incidence and outcomes of SARS-CoV-2 reinfection before the period of Omicron (B.1.1.529) predominance. We assessed risk of bias using Joanna Briggs Institute critical appraisal tools and conducted meta-analyses with random effects models to estimate the proportion of SARS-CoV-2 reinfection among initially infected cases and hospitalisation and mortality proportions among reinfected ones. Results: We identified 7593 studies and extracted data from 64 included ones representing 21 countries. The proportion of SARS-CoV-2 reinfection was 1.16% (95% confidence interval (CI) = 1.01-1.33) based on 11 639 247 initially infected cases, with ≥45 days between the two infections. Healthcare providers (2.28%; 95% CI = 1.37-3.40) had a significantly higher risk of reinfection than the general population (1.00%; 95% CI = 0.81-1.20), while young adults aged 18 to 35 years (1.01%; 95% CI = 0.8-1.25) had a higher reinfection burden than other age groups (children <18 years old: 0.57%; 95% CI = 0.39-0.79, older adults aged 36-65 years old: 0.53%; 95% CI = 0.41-0.65, elderly >65 years old: 0.37%; 95% CI = 0.15-0.66). Among the reinfected cases, 8.12% (95% CI = 5.30-11.39) were hospitalised, 1.31% (95% CI = 0.29-2.83) were admitted to the intensive care unit, and 0.71% (95% CI = 0.02-2.01) died. Conclusions: Our data suggest a relatively low risk of SARS-CoV-2 reinfection in the pre-Omicron era, but the risk of hospitalisation was relatively high among the reinfected cases. Considering the possibility of underdiagnosis, the reinfection burden may be underestimated. Registration: PROSPERO: CRD42023449712.

Incidence of Omicron Variant Reinfection and Reduction of Reinfection Risk After Coronavirus Disease 2019 Vaccination in Children.

Data are limited on the incidence of coronavirus disease 2019 (COVID-19) reinfection in children. This population-based cohort study in Niigata, Japan from January to November 2022 demonstrated the incidence of reinfection was 1337/48 099 (2.8%), and the hazard ratio for reinfection in vaccinated children was 0.29 (95% confidence interval, 0.20-0.40).