Risk of reinfection and severity with the predominant BA.5 Omicron subvariant China, from December 2022 to January 2023.

Data on reinfection in large Asian populations are limited. In this study, we aimed to evaluate the reinfection rate, disease severity, and time interval between the infections in the symptomatic and asymptomatic populations which are firstl infected with BA.2 Omicron Variant. We retrospectively included adult patients with COVID-19 discharged from four designated hospitals between 27 April 2021 and 30 November 2022, who were interviewed via telephone from 29 January to 1 March 2023. Univariable and multivariable analyses were used to explore risk factors associated with reinfection. A total of 16,558 patients were followed up, during the telephone survey of an average of 310.0 days, 1610 (9.72%) participants self-reported reinfection. The mean time range of reinfection was 257.9 days. The risks for reinfection were analysed using multivariable logistic regression. Patients with severe first infection were at higher risk for reinfection (aORs, 2.50; P < 0.001). The male (aORs,0.82; P < 0.001), the elderly (aORs, 0.44; P < 0.001), and patients with full vaccination (aORs, 0.67; P < 0.001) or booster (aORs, 0.63; P < 0.001) had the lower risk of reinfection. Patients over 60 years of age (aORs,9.02; P = 0.006) and those with ≥2 comorbidities (aORs,11.51; P = 0.016). were at higher risk for severe reinfection. The number of clinical manifestations of reinfection increases in people with severe first infection (aORs, 2.82; P = 0.023). The overall reinfection rate was 9.72%, and the reinfection rate of Omicron-to-Omicron subvariants was 9.50% at one year. The severity of Omicron-Omicron reinfection decreased. Data from our clinical study may provide clinical evidence and bolster response preparedness for future COVID-19 reinfection waves.

Neutralization against Omicron subvariants after BA.5/BF.7 breakthrough infection weakened as virus evolution and aging despite repeated prototype-based vaccination1.

BACKGROUND: Omicron had swept the mainland China between December 2022 and January 2023, while SARS-CoV-2 still continued to evolve. To fully prepare for the next wave, it's urgent to evaluate the humoral immune response post BA.5/BF.7 breakthrough infection against predominant sub-lineages among existing vaccination strategies and the elders. METHOD: This study enrolled a longitudinal young-adult cohort from 2/3-dose vaccination to 1 month after breakthrough infection, and an elder cohort at 1 month after breakthrough infection. Seral samples were collected and tested for humoral immune response to SARS-CoV-2 subvariants including WT, BA.2, BA.5, BF.7, BQ.1.1, CH.1.1, XBB.1.5. RESULTS: BA.5/BF.7 breakthrough infection induced higher neutralization activity than solely vaccination in all SARS-CoV-2 strains, while the latest Omicron subvariants, BQ.1.1, CH.1.1, XBB.1.5, exhibited the strongest neutralization evasion ability. There was a negative correlation between age and humoral immune response in WT, BA.5, BQ.1.1, and XBB.1.5. Compared to non-vaccination groups, breakthrough infection in two-dose vaccination groups had significantly higher neutralizing antibody against WT, BA.2, BA.5, BF.7 but not to BQ.1.1, CH.1.1, XBB.1.5 while booster dose against the prototype prior-breakthrough would not further significantly enhance individual's humoral responses against the latest Omicron subvariants. CONCLUSIONS: Newer variants manifest increasing immune evasion from neutralization and repeated prototype-based booster vaccines may not further enhance neutralizing antibody against emerging new variants. Older adults have lower levels of neutralizing antibody. Future vaccination strategies should aim to enhance effective neutralization to contemporary variants.

A one-year follow-up study of systematic impact of long COVID symptoms among patients post SARS-CoV-2 omicron variants infection in Shanghai, China.

Long COVID hinders people from normal life and work, posing significant medical and economic challenges. Nevertheless, comprehensive studies assessing its impact on large populations in Asia are still lacking. We tracked over 20,000 patients infected with COVID-19 for the first time during the Omicron BA.2 outbreak in Shanghai from March-June 2022 for one year. Of the 21,799 COVID-19 patients who participated in the 6-month telephone follow-up, 1939 (8.89%) had self-reported long COVID symptoms. 450 long COVID patients participated in the 6-month outpatient follow-up. Participants underwent healthy physical examinations and questionnaires focused on long-COVID-related symptoms and mental health. Mobility problem (P < 0.001), personal care problem (P = 0.003), usual activity problem (P < 0.001), pain/discomfort (P < 0.001), anxiety/depression (P = 0.001) and PTSD (P = 0.001) were more prevalent in long COVID patients than in healthy individuals, but no significant differences were found between the two groups on chest CT and laboratory examinations. Of the 856 long COVID patients who participated in the 12-month follow-up, 587 (68.5%) had their symptoms resolved. In the multivariable logistic analysis, females (P < 0.001), youth (age <40 years) (P < 0.001), ≥ 2 comorbidities (P = 0.009), and severe infection in the acute phase (P = 0.006) were risk factors for developing long COVID. Middle age (40-60 years) was a risk factor for persistent long COVID one year after hospital discharge (P = 0.013). The study found that long COVID mainly manifested as subjective symptoms and impacts partial patients' quality of life and mental status. After one year, most (68.5%) of the patients recovered from long COVID with no impairment of organ function observed.