Abstract:What is already known about this topic?
The first nationwide wave of coronavirus disease 2019 (COVID-19), driven by the Omicron variant, has largely subsided. However, subsequent epidemic waves are inevitable due to waning immunity and the ongoing evolution of the severe acute respiratory syndrome coronavirus 2.
What is added by this report?
Insights gleaned from other nations offer guidance regarding the timing and scale of potential subsequent waves of COVID-19 in Chi… Show more
“…The peak of infectious individuals in the second wave and the third wave is 1/9 and 1/18 (5.5%) of the first wave, respectively, and the epidemic time is longer than that of the first wave. The results is similar to the results of the “pre-planned study” published in CDC weekly which examines the second wave of infections in different regions and populations around the world ( Niu et al., 2023 ; Zhang et al., 2023 ). Fig.…”
“…The peak of infectious individuals in the second wave and the third wave is 1/9 and 1/18 (5.5%) of the first wave, respectively, and the epidemic time is longer than that of the first wave. The results is similar to the results of the “pre-planned study” published in CDC weekly which examines the second wave of infections in different regions and populations around the world ( Niu et al., 2023 ; Zhang et al., 2023 ). Fig.…”
“…It has been over three years since the COVID-19 pandemic was first identified in December 2019 [ 13 ]. Due to the implementation of the dynamic zero-COVID policy and the vigorous promotion of the three-shot inactivated vaccine in China, the country experienced its first nationwide wave of COVID-19 caused by the Omicron variant considerably later than other nations [ 14 ]. After the release of “the 10-point measures” in China at the end of 2022 [ 6 ], the Omicron variant spread widely and simultaneously among the general population, causing two epidemic waves [ 15 ] during the observation period of our cohort from December 2022 to July 2023.…”
Background: After the adjustment of COVID-19 epidemic policy, mainland China experienced two consecutive waves of Omicron variants within a seven-month period. In Guangzhou city, as one of the most populous regions, the viral infection characteristics, molecular epidemiology, and the dynamic of population immunity are still elusive. Methods: We launched a prospective cohort study in the Guangdong Provincial CDC from December 2022 to July 2023. Fifty participants who received the same vaccination regimen and had no previous infection were recruited. Results: 90% of individuals were infected with Omicron BA.5* variants within three weeks in the first wave. Thirteen cases (28.26%) experienced infection with XBB.1* variants, occurring from 14 weeks to 21 weeks after the first wave. BA.5* infections exhibited higher viral loads in nasopharyngeal sites compared to oropharyngeal sites. Compared to BA.5* infections, the XBB.1* infections had significantly milder clinical symptoms, lower viral loads, and shorter durations of virus positivity. The infection with the BA.5* variant elicited varying levels of neutralizing antibodies against XBB.1* among different individuals, even with similar levels of BA.5* antibodies. The level of neutralizing antibodies specific to XBB.1* determined the risk of reinfection. Conclusions: The rapid large-scale infections of the Omicron variants have quickly established herd immunity among the population in mainland China. In the future of the COVID-19 epidemic, a lower infection rate but a longer duration can be expected. Given the large population size and ongoing diversified herd immunity, it remains crucial to closely monitor the molecular epidemiology of SARS-CoV-2 for the emergence of new variants of concern in this region. Additionally, the timely evaluation of the immune status across different age groups is essential for informing future vaccination strategies and intervention policies.
“…In our study, a total 222 patients received at least one dose (4 doses, n = 3; 3 doses, n = 130; 2 doses, n = 53; 1 dose, n = 36), showing consistent results with these reports. The SARS-CoV-2 omicron is the main variant causing the epidemic wave of COVID-19 between November 2021 and February 2023 in 189 countries ( Niu et al, 2023 ). The eventual cancellation of zero COVID-19 policy in China on December 7, 2022 contributed to an unprecedented large-scale omicron wave in December 2022 together with a sharp rise in influenza incidence in February 2023 ( Zeng et al, 2023 ).…”
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