ABSTRACT
Between 2 and 8.5% of patients who recover from COVID-19 do not develop antibodies, and the durability of IgG antibodies is under scrutiny. Therefore, the presence and persistence of IgM and IgG antibodies were evaluated in a group of patients diagnosed with SARS-CoV-2 from May to August 2020. Out of 2199 suspected COVID-19 cases, 1264 were confirmed for SARS-CoV-2 by rRT-PCR; 328 consented to participate in the study, with 220 participants followed for 9 months, including 124 men (56%) and 96 women (44%). The primary symptoms were headache, dry cough, and fever. IgG antibodies developed in 95% of patients within 4 weeks post-diagnosis, and a second evaluation at 9 months showed that 72.7% still had detectable IgG antibodies. The presence of IgM in one individual (0.45%) suggested the possibility of reinfection.
ABSTRACT
In late March 2020, SARS-CoV-2 arrived in Manaus, Brazil, and rapidly developed into a large-scale epidemic that collapsed the local health system and resulted in extreme death rates. Several key studies reported that â¼76% of residents of Manaus were infected (attack rate AR≃76%) by October 2020, suggesting protective herd immunity had been reached. Despite this, an unexpected second wave of COVID-19 struck again in November and proved to be larger than the first, creating a catastrophe for the unprepared population. It has been suggested that this could be possible if the second wave was driven by reinfections. However, it is widely reported that reinfections were at a low rate (before the emergence of Omicron), and reinfections tend to be mild. Here, we use novel methods to model the epidemic from mortality data without considering reinfection-caused deaths and evaluate the impact of interventions to explain why the second wave appeared. The method fits a "flexible" reproductive number R0(t) that changes over the epidemic, and it is demonstrated that the method can successfully reconstruct R0(t) from simulated data. For Manaus, the method finds AR≃34% by October 2020 for the first wave, which is far less than required for herd immunity yet in-line with seroprevalence estimates. The work is complemented by a two-strain model. Using genomic data, the model estimates transmissibility of the new P.1 virus lineage as 1.9 times higher than that of the non-P.1. Moreover, an age class model variant that considers the high mortality rates of older adults show very similar results. These models thus provide a reasonable explanation for the two-wave dynamics in Manaus without the need to rely on large reinfection rates, which until now have only been found in negligible to moderate numbers in recent surveillance efforts.
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We generated 238 Zika virus (ZIKV) genomes from 135 persons in Brazil who had samples collected over 1 year to evaluate virus persistence. Phylogenetic inference clustered the genomes together with previously reported ZIKV strains from northern Brazil, showing that ZIKV has been remained relatively stable over time. Temporal phylogenetic analysis revealed limited within-host diversity among most ZIKV-persistent infected associated samples. However, we detected unusual virus temporal diversity from >5 persons, uncovering the existence of divergent genomes within the same patient. All those patients showed an increase in neutralizing antibody levels, followed by a decline at the convalescent phase of ZIKV infection. Of interest, in 3 of those patients, titers of neutralizing antibodies increased again after 6 months of ZIKV infection, concomitantly with real-time reverse transcription PCR re-positivity, supporting ZIKV reinfection events. Altogether, our findings provide evidence for the existence of ZIKV reinfection events.
Subject(s)
Zika Virus Infection , Zika Virus , Humans , Zika Virus/genetics , Zika Virus Infection/epidemiology , Antibody Formation , Brazil/epidemiology , Phylogeny , Reinfection , Antibodies, NeutralizingABSTRACT
Worldwide, Urinary Tract Infections (UTIs) are an important health problem with many cases reported annually, women being the most affected. UTIs are relevant because they can become a recurrent condition, associated with different factors that contribute to the chronicity of the disease (cUTI). cUTI can be classified as persistent (peUTI) when the causative agent is the same each time the infection occurs or as reinfection (reUTI) when the associated microorganism is different. The purpose of this work was to characterize Escherichia coli isolates obtained in two prospective studies of patients with cUTI, to define which of them corresponded to peUTI and which to reUTI. A total of 394 isolates of E. coli were analyzed by agglutination with specific sera, antimicrobial susceptibility by diffusion disc test, and the phylogroups and presence of genes associated with virulence by PCR assays. Additionally, in some characterized strains adherence, invasiveness, and biofilm formation were analyzed by in vitro assays. The results showed that the peUTI strains belonged mainly to the classical UPEC serogroups (O25, O75, O6), were included in the B2 phylogroup, carried a great number of virulence genes, and were adherent, invasive, and biofilm-forming. Meanwhile, reUTI strains showed great diversity of serogroups, belonged mainly in the A phylogroup, and carried fewer virulence genes. Both peUTI and reUTI strains showed extensively drug-resistant (XDR) and multidrug-resistant (MDR) profiles in the antimicrobial susceptibility test. In conclusion, it appears that peUTIs are caused principally by classical UPEC strains, while reUTIs are caused by strains that appear to be a part of the common E. coli intestinal biota. Moreover, although both peUTI and reUTI strains presented different serotypes and phylogroups, their antimicrobial resistance profile (XDR and MDR) was similar, confirming the importance of regulating prophylactic treatments and seeking alternatives for the treatment and control of cUTI. Finally, it was possible to establish the features of the E. coli strains responsible for peUTI and reUTI which could be helpful to develop a fast diagnostic methodology.
Subject(s)
Anti-Infective Agents , Escherichia coli Infections , Urinary Tract Infections , Humans , Female , Escherichia coli/genetics , Follow-Up Studies , Escherichia coli Infections/diagnosis , Prospective Studies , Virulence Factors/analysis , Virulence Factors/genetics , Urinary Tract Infections/diagnosisABSTRACT
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.
Subject(s)
COVID-19 , SARS-CoV-2 , Female , Humans , Middle Aged , Aged , COVID-19/epidemiology , Reinfection/epidemiology , Case-Control Studies , Risk FactorsABSTRACT
El síndrome inflamatorio multisistémico pediátrico (MIS-C, por su sigla en inglés) es una enfermedad rara. Se desconoce si los niños que se recuperaron del MIS-C tienen riesgo de recurrencia de MIS-C cuando presentan reinfección por SARS-CoV-2. El objetivo de este estudio es describir los casos de dos niñas que se recuperaron del MIS-C y presentaron reinfección por SARS-CoV-2 sin recurrencia de MIS-C.
Multisystem inflammatory syndrome in children (MIS-C) is a rare condition. It is still unknown if children who have recovered from MIS-C are at a risk of recurrence of MIS-C when they are reinfected with SARS-CoV-2. In this study, we aimed to report 2 children who recovered from MIS-C and reinfected with SARS-CoV-2 without recurrence of MIS-C.
Subject(s)
Humans , Female , Child , SARS-CoV-2 , COVID-19/complications , Systemic Inflammatory Response Syndrome/diagnosis , Systemic Inflammatory Response Syndrome/therapyABSTRACT
Introducción: La pandemia de COVID-19 afectó significativamente al personal de salud, los estudiantes de medicina tuvieron alta exposición a la infección y reinfección. El objeto del estudio fue determinar la infección y reinfección por SARS-Cov-2 y la cobertura vacunal en los estudiantes de medicina de 1ro a 6to año en el período de enero-febrero 2023. Metodología: Estudio de corte transversal por encuesta vía electrónica. Muestra aleatoria polietápica por azar simple y conglomerados estratificados por nivel académico. Proyecto avalado por La Comisión Nacional de Bioética. Resultados: Se recolectaron 224 respuestas, reportando 334 episodios de infección por SARS-CoV-2, 19 % presentó al menos un episodio de infección en 2020, 40 % en 2021 y 41 % en 2022. El 75,4 % reportó haber estado infectado y reinfectado; de estos, el 70 % presentó entre 2 y 5 reinfecciones. En el 37 % de los episodios se confirmó, por reacción en cadena polimerasa (PCR, por sus siglas en inglés) o prueba de antígenos. Los estudiantes de internado rotatorio y 5to año se infectaron más que los de 1ro a 3er año (p= 0,0037). La vacunación alcanzó 96 % de los estudiantes, la mayoría recibió 2 o más dosis de refuerzo, los alumnos de 4to a 6to año con un número mayor de dosis (p= 0,0067). Las hospitalizaciones fueron bajas 4 %. Conclusiones: las infecciones y reinfecciones son frecuentes en los estudiantes de medicina; la mayoría no presenta complicaciones graves, los estudiantes del área clínica están más expuestos y están mayormente vacunados, que los estudiantes de preclínica.
Introduction: The COVID-19 pandemic significantly impacted healthcare personnel, with medical students having high exposure to infection and reinfection. The study aimed to determine the infection and reinfection rates of SARS-CoV-2 and the vaccination coverage among medical students from 1st to 6th year during the period of January-February 2023. Methodology: This was a cross-sectional study using an electronic survey. A multi-stage random sample was taken with simple random sampling and clusters stratified by academic level. The project was approved by the National Bioethics Commission. Results: A total of 224 responses were collected, reporting 334 episodes of SARS-CoV-2 infection. Nineteen percent reported at least one episode of infection in 2020, 40 % in 2021, and 41 % in 2022. Seventy-five point four percent reported having been infected and reinfected; of these, 70 % had between 2 and 5 reinfections. In 37 % of the episodes, the infection was confirmed by polymerase chain reaction (PCR) or antigen test. Internship students and 5th-year students were more infected than those in 1st to 3rd year (p=0.0037). Vaccination coverage reached 96 % of the students, with most receiving 2 or more booster doses; students in the 4th to 6th years had a higher number of doses (p=0.0067). Hospitalizations were low at 4 %. Conclusions: Infections and reinfections are frequent among medical students; most do not present severe complications. Clinical area students are more exposed to infection and are more vaccinated compared to preclinical students.
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BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic began in Brazil on 26 February 2020. By 6 May 2023, 37.4 million cases had been confirmed, causing 701 thousand deaths in the country. We aimed to describe the epidemiological profile and clinical development of COVID-19 cases among the employees of a health institution, from acute infection to long COVID. METHODS: This was a longitudinal study using a retrospective and prospective approach via questionnaires referring to epidemiological investigation, which was the inclusion criteria, and about long-term symptoms. RESULTS: A total of 809 employees were detected with SARS-CoV-2 infection via RT-PCR, 466 of them answered the epidemiological investigation, and 101 completed the Long COVID Symptom Questionnaire. The most commonly affected employees were women (88.6%) working in patient care (68.6%). Headache, myalgia, cough, odynophagia, and runny nose were the most frequent symptoms. Only three employees (0.6%) required hospitalization, while the other employees required outpatient management due to mild symptoms. We identified 19 (4.1%) cases of reinfection, and 42 (41.6%) employees reported long-term symptoms, such as myalgia, dyspnea, and headache. CONCLUSIONS: Although most cases were mild with good outcomes, long COVID cases identified are noteworthy, as these symptoms may impact quality of life even months after SARS-CoV-2 infection.
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Introduction: The pandemic caused by SARS-CoV-2 has had a major impact on health systems. Vaccines have been shown to be effective in improving the clinical outcome of COVID-19, but they are not able to fully prevent infection and reinfection, especially that caused by new variants. Methods: Here, we tracked for 450 days the humoral immune response and reinfection in 52 healthcare workers from Brazil. Infection and reinfection were confirmed by RT-qPCR, while IgM and IgG antibody levels were monitored by rapid test. Results: Of the 52 participants, 19 (36%) got reinfected during the follow-up period, all presenting mild symptoms. For all participants, IgM levels dropped sharply, with over 47% of them becoming seronegative by the 60th day. For IgG, 90% of the participants became seropositive within the first 30 days of follow-up. IgG antibodies also dropped after this period reaching the lowest level on day 270 (68.5 ± 72.3, p<0.0001). Booster dose and reinfection increased the levels of both antibodies, with the interaction between them resulting in an increase in IgG levels of 130.3 arbitrary units. Conclusions: Overall, our data indicate that acquired humoral immunity declines over time and suggests that IgM and IgG antibody levels are not associated with the prevention of reinfection.
Subject(s)
COVID-19 , Immunity, Humoral , Humans , SARS-CoV-2 , Brazil/epidemiology , Longitudinal Studies , Reinfection , Immunoglobulin G , Health Personnel , Immunoglobulin MABSTRACT
Introduction: As the SARS-CoV-2 continues to evolve, new variants pose a significant threat by potentially overriding the immunity conferred by vaccination and natural infection. This scenario can lead to an upswing in reinfections, amplified baseline epidemic activity, and localized outbreaks. In various global regions, estimates of breakthrough cases associated with the currently circulating viral variants, such as Omicron, have been reported. Nonetheless, specific data on the reinfection rate in Chile still needs to be included. Methods: Our study has focused on estimating COVID-19 reinfections per wave based on a sample of 578,670 RT-qPCR tests conducted at the University of Santiago of Chile (USACH) from April 2020 to July 2022, encompassing 345,997 individuals. Results: The analysis reveals that the highest rate of reinfections transpired during the fourth and fifth COVID-19 waves, primarily driven by the Omicron variant. These findings hold despite 80% of the Chilean population receiving complete vaccination under the primary scheme and 60% receiving at least one booster dose. On average, the interval between initial infection and reinfection was found to be 372 days. Interestingly, reinfection incidence was higher in women aged between 30 and 55. Additionally, the viral load during the second infection episode was lower, likely attributed to Chile's high vaccination rate. Discussion: This study demonstrates that the Omicron variant is behind Chile's highest number of reinfection cases, underscoring its potential for immune evasion. This vital epidemiological information contributes to developing and implementing effective public health policies.
Subject(s)
COVID-19 , SARS-CoV-2 , Humans , Female , Adult , Middle Aged , SARS-CoV-2/genetics , COVID-19/diagnosis , COVID-19/epidemiology , Chile/epidemiology , Reinfection/epidemiologyABSTRACT
Since the beginning of the SARS-CoV-2 pandemic, studies on the variants and sublineages stand out, mainly in the cases of reinfection in a short period. In this study, we describe a case of infection by BA.1.1 sublineage in an individual from Southern Brazil. The same patient acquired reinfection with sublineage BA.2 within 16 days after the first detection. The viral extraction and RT-qPCR were performed on the samples LMM72045 (collected in May 2022) and LMM72044 (collected in June 2022). After the confirmation of SARS-CoV-2 infection, we conducted the sequencing and viral genome analysis. This case of reinfection affected a 52-year-old male patient, without comorbidities, with three doses of vaccines against COVID-19, showing symptoms on May 19. These symptoms lasted for approximately six days. The patient returned to work activities on May 30. However, on June 4, the patient felt a new round of clinical signs that lasted for approximately seven days. Analysis of the viral genomes recovered from patients' clinical samples revealed that the two COVID-19 episodes were related to two divergent VOC Omicron sublineages, namely, BA.1.1 for the first round of symptoms and BA.2 for the second infection. Based on our findings, we can say that the present case of reinfection is the shortest described so far.
Subject(s)
COVID-19 , SARS-CoV-2 , Male , Humans , Middle Aged , SARS-CoV-2/genetics , COVID-19/diagnosis , Reinfection , COVID-19 Vaccines , Brazil/epidemiologyABSTRACT
Mpox is caused by a zoonotic orthopoxvirus capable of infecting several animal species, including humans. The analysis of cases in the current outbreak showed that, differently from what happens in the classical disease, mpox has mostly affected men who have sex with men (MSM) and bisexuals, including a high proportion of people living with HIV/AIDS. The role of the immune system in fighting mpox has been discussed in literature and experts believe that immunity conferred by natural infection may be lifelong, advocating against the possibility of reinfection by monkeypox virus. This report presents a MSM couple living with HIV with cycles of mpox lesions after two different risk exposures. The clinical course of both cases, as well as the temporal and anatomical relationship between the second cycle of monkeypox virus lesions and the second exposure, suggests the occurrence of reinfection. The genomic surveillance of monkeypox virus, a better understanding of its interaction with the human host, and knowledge of the postinfection and postvaccine protection correlation are more relevant at this moment, when we observe an intersection of the mpox multicountry outbreak with the HIV/AIDS epidemic, considering the immunosenescence and other immune system issues caused by HIV.
Subject(s)
Acquired Immunodeficiency Syndrome , HIV Infections , Mpox (monkeypox) , Sexual and Gender Minorities , Animals , Male , Humans , Reinfection , Homosexuality, Male , Mpox (monkeypox)/epidemiology , HIV Infections/complications , Chronic DiseaseABSTRACT
Background: With the widespread transmission of the Omicron SARS-CoV-2 variant, reinfections have become increasingly common. Here, we explored the role of immunity, primary infection severity, and variant predominance in the risk of reinfection and severe COVID-19 during Omicron predominance in Mexico. Methods: We analyzed reinfections in Mexico in individuals with a primary infection separated by at least 90 days from reinfection using a national surveillance registry of SARS-CoV-2 cases from March 3rd, 2020, to August 13th, 2022. Immunity-generating events included primary infection, partial or complete vaccination, and booster vaccines. Reinfections were matched by age and sex with controls with primary SARS-CoV-2 infection and negative RT-PCR or antigen test at least 90 days after primary infection to explore reinfection and severe disease risk factors. We also compared the protective efficacy of heterologous and homologous vaccine boosters against reinfection. Results: We detected 231,202 SARS-CoV-2 reinfections in Mexico, most occurring in unvaccinated individuals (41.55%). Over 207,623 reinfections occurred during periods of Omicron (89.8%), BA.1 (36.74%), and BA.5 (33.67%) subvariant predominance and a case-fatality rate of 0.22%. Vaccination protected against reinfection, without significant influence of the order of immunity-generating events and provided >90% protection against severe reinfections. Heterologous booster schedules were associated with ~11% and ~ 54% lower risk for reinfection and reinfection-associated severe COVID-19, respectively, modified by time-elapsed since the last immunity-generating event, when compared against complete primary schedules. Conclusion: SARS-CoV-2 reinfections increased during Omicron predominance. Hybrid immunity provides protection against reinfection and associated severe COVID-19, with potential benefit from heterologous booster schedules.
Subject(s)
COVID-19 , SARS-CoV-2 , Humans , COVID-19/epidemiology , COVID-19/prevention & control , Reinfection/epidemiology , Mexico/epidemiology , Adaptive ImmunityABSTRACT
BACKGROUND: Repeated SARS-CoV-2 infections are plausible and related published data are scarce. We aimed to identify factors associated with the risk of recurrent (three episodes) laboratory-confirmed symptomatic SARS-CoV-2 infections. METHODS: A retrospective cohort study was conducted, and 1,700 healthcare workers were enrolled. We used risk ratios (RR) and 95% confidence intervals (CI) to evaluate the factors associated with symptomatic SARS-CoV-2 infections. RESULTS: We identified 14 participants with recurrent illness episodes. Therefore, the incidence rate was 8.5 per 10,000 person months. In a multiple-model study, vaccinated adults (vs. unvaccinated, RR = 1.05 [1.03-1.06]) and those with a severe first illness episode (vs. mild disease, RR = 1.05 [1.01-1.10]) were at increased risk for repeated symptomatic SARS-CoV-2 reinfections. Increasing age showed a protective effect (per each additional year of age: RR = 0.98 [0.97-0.99]). CONCLUSIONS: Our results suggest that recurrent SARS-CoV-2 infections are rare events in adults, and they seem to be determined, partially, by vaccination status and age.
ABSTRACT
A healthy young man first diagnosed with mpox in May 2022 presented again in November 2022 with anal proctitis and a positive polymerase chain reaction on a rectal swab for Monkeypox virus after a recent trip to Brazil, where he engaged in condomless sexual intercourse with multiple male partners.
Subject(s)
Mpox (monkeypox) , Humans , Male , Reinfection , Brazil , Monkeypox virus , Polymerase Chain ReactionABSTRACT
Multisystem inflammatory syndrome in children (MIS-C) is a rare condition. It is still unknown if children who have recovered from MIS-C are at a risk of recurrence of MIS-C when they are reinfected with SARSCoV-2. In this study, we aimed to report 2 children who recovered from MIS-C and reinfected with SARSCoV-2 without recurrence of MIS-C.
El síndrome inflamatorio multisistémico pediátrico (MIS-C, por su sigla en inglés) es una enfermedad rara. Se desconoce si los niños que se recuperaron del MIS-C tienen riesgo de recurrencia de MIS-C cuando presentan reinfección por SARS-CoV-2. El objetivo de este estudio es describir los casos de dos niñas que se recuperaron del MIS-C y presentaron reinfección por SARS-CoV-2 sin recurrencia de MIS-C.
Subject(s)
COVID-19 , SARS-CoV-2 , Child , Humans , COVID-19/complications , Systemic Inflammatory Response Syndrome/diagnosis , Systemic Inflammatory Response Syndrome/therapyABSTRACT
COVID-19 has taken a severe toll on the global population through infections, hospitalizations, and deaths. Elucidating SARS-CoV-2 infection-derived immunity has led to the development of multiple effective COVID-19 vaccines and their implementation into mass-vaccination programs worldwide. After ~3 years, a substantial proportion of the human population possesses immunity from infection and/or vaccination. With waning immune protection over time against emerging SARS-CoV-2 variants, it is essential to understand the duration of protection, breadth of coverage, and effects on reinfection. This targeted review summarizes available research literature on SARS-CoV-2 infection-derived, vaccination-elicited, and hybrid immunity. Infection-derived immunity has shown 93-100% protection against severe COVID-19 outcomes for up to 8 months, but reinfection is observed with some virus variants. Vaccination elicits high levels of neutralizing antibodies and a breadth of CD4+ and CD8+ T-cell responses. Hybrid immunity enables strong, broad responses, with high-quality memory B cells generated at 5- to 10-fold higher levels, versus infection or vaccination alone and protection against symptomatic disease lasting for 6-8 months. SARS-CoV-2 evolution into more transmissible and immunologically divergent variants has necessitated the updating of COVID-19 vaccines. To ensure continued protection against SARS-CoV-2 variants, regulators and vaccine technical committees recommend variant-specific or bivalent vaccines.
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OBJECTIVES: To characterize the timing and genotype distribution of symptomatic and asymptomatic sapovirus infections and re-infections in a Nicaraguan birth cohort. METHODS: Infants (N = 444) were enrolled at 10-14 days of life and observed weekly until 2 years of age. Stool samples were collected for each acute gastroenteritis (AGE) episode, and routine stool samples were collected monthly. Stool samples were tested for sapovirus using RT-qPCR, and positive samples were genotyped. RESULTS: A total of 348 children completed 2 years of AGE weekly surveillance; 93 (26.7%) of them experienced sapovirus AGE. Most infections occurred after 5 months of age and mainly during the second year of life (62.4%, 58/93) and early in the rainy season. Sapovirus screening in all stools from a subset of 67 children who consistently provided samples showed sapovirus infections in 91 of 330 (27.6%) AGE episodes and in 39 of 1350 (2.9%) routine stools. In this subset, the median age at the first sapovirus AGE was 11.2 months (95% CI, 9.3-15.9 months); 38 of 67 (57%) children experienced re-infections, 19 symptomatic and 19 asymptomatic. On average, sapovirus re-infections were reported 7.2 months after symptomatic and 5.3 months after asymptomatic infections. Genogroup GI (64%, 69/108) was the most common detected. Sapovirus GI.1 was more frequently detected in AGE stool samples than in routine stool samples (47.2%, 43/91 vs. 25.6%, 10/39; p 0.005), and re-infection with the same genotype was uncommon. DISCUSSION: The first sapovirus infections occurred at approximately 11 months of age, whereas the median time to symptomatic re-infection was 7.2 months. Re-infections with the same sapovirus genotype were rare during 2 years of life suggesting genotype-specific protection after natural infection.
Subject(s)
Caliciviridae Infections , Sapovirus , Infant , Child , Humans , Reinfection , Sapovirus/genetics , Birth Cohort , Asymptomatic Infections/epidemiology , Caliciviridae Infections/epidemiology , Caliciviridae Infections/diagnosis , Phylogeny , Genotype , FecesABSTRACT
BACKGROUND: Much of the world's population has been infected with SARS-CoV-2. Thus, immunity from prior infection will play a critical role in future SARS-CoV-2 transmission. We investigated the impact of infection-induced immunity on viral shedding duration and viral load. METHODS: We conducted a household cohort study in Managua, Nicaragua, with an embedded transmission study that closely monitors participants regardless of symptoms. Real-time reverse-transcription polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assays (ELISAs) were used to measure infections and seropositivity, respectively. Blood samples were collected twice annually and surrounding household intensive monitoring periods. We used accelerated failure time models to compare shedding times. Participants vaccinated ≥14 days prior to infection were excluded from primary analyses. RESULTS: There were 600 RT-PCR-confirmed SARS-CoV-2 infections in unvaccinated participants between May 1, 2020, and March 10, 2022, with prior ELISA data. Prior infection was associated with 48% shorter shedding times (event time ratio [ETR] 0.52, 95% CI: 0.39-0.69, mean shedding: 13.7 vs. 26.4 days). A fourfold higher anti-SARS-CoV-2 spike titer was associated with 17% shorter shedding (ETR 0.83, 95% CI: 0.78-0.90). Similarly, maximum viral loads (lowest cycle threshold [CT]) were lower for previously infected individuals (mean CT 29.8 vs. 28.0, p = 4.02 × 10-3 ), for adults and children ≥10 years, but not for children 0-9 years; there was little difference in CT levels for previously infected versus naïve adults aged above 60 years. CONCLUSIONS: Prior infection-induced immunity was associated with shorter viral shedding and lower viral loads, which may be important in the transition from pandemic to endemicity.
Subject(s)
COVID-19 , Adult , Child , Humans , COVID-19/epidemiology , SARS-CoV-2 , Cohort Studies , Virus Shedding , COVID-19 TestingABSTRACT
Rare cases of suspected COVID-19 reactivation have been reported. Reactivation is defined by two positive real-time RT-PCR results for the SARS-CoV-2 virus, with an interval equal to or greater than 90 days between two episodes of COVID-19. A nurse, started with COVID-19 symptoms in July 2020 and a RT-PCR SARS-CoV-2 confirmed the diagnosis. In November 2020, more than 4 months later, she developed a new episode of COVID-19 confirmed by a second RT-PCR SARS-CoV-2. The patient received a first dose of CoronaVac (Sinovac/Butantan) in January 2021 and a second dose in February 2021, but 30 days after a third episode was confirmed. Contrary to what happens with many infectious diseases which generate antibodies and protect people from future episodes, this aspect is still not clear in relation to COVID-19. In addition to vaccination, the use of Personal Protective Equipment is essential for healthcare workers.