TY - JOUR
T1 - Contribution of low population immunity to the severe Omicron BA.2 outbreak in Hong Kong
AU - Chen, Lin Lei
AU - Abdullah, Syed Muhammad Umer
AU - Chan, Wan Mui
AU - Chan, Brian Pui Chun
AU - Ip, Jonathan Daniel
AU - Chu, Allen Wing Ho
AU - Lu, Lu
AU - Zhang, Xiaojuan
AU - Zhao, Yan
AU - Chuang, Vivien Wai Man
AU - Au, Albert Ka Wing
AU - Cheng, Vincent Chi Chung
AU - Sridhar, Siddharth
AU - Yuen, Kwok Yung
AU - Hung, Ivan Fan Ngai
AU - Chan, Kwok Hung
AU - To, Kelvin Kai Wang
N1 - Publisher Copyright:
© 2022, The Author(s).
PY - 2022/12
Y1 - 2022/12
N2 - Monitoring population protective immunity against SARS-CoV-2 variants is critical for risk assessment. We hypothesize that Hong Kong’s explosive Omicron BA.2 outbreak in early 2022 could be explained by low herd immunity. Our seroprevalence study using sera collected from January to December 2021 shows a very low prevalence of neutralizing antibodies (NAb) against ancestral virus among older adults. The age group-specific prevalence of NAb generally correlates with the vaccination uptake rate, but older adults have a much lower NAb seropositive rate than vaccination uptake rate. For all age groups, the seroprevalence of NAb against Omicron variant is much lower than that against the ancestral virus. Our study suggests that this BA.2 outbreak and the exceptionally high case-fatality rate in the ≥80 year-old age group (9.2%) could be attributed to the lack of protective immunity in the population, especially among the vulnerable older adults, and that ongoing sero-surveillance is essential.
AB - Monitoring population protective immunity against SARS-CoV-2 variants is critical for risk assessment. We hypothesize that Hong Kong’s explosive Omicron BA.2 outbreak in early 2022 could be explained by low herd immunity. Our seroprevalence study using sera collected from January to December 2021 shows a very low prevalence of neutralizing antibodies (NAb) against ancestral virus among older adults. The age group-specific prevalence of NAb generally correlates with the vaccination uptake rate, but older adults have a much lower NAb seropositive rate than vaccination uptake rate. For all age groups, the seroprevalence of NAb against Omicron variant is much lower than that against the ancestral virus. Our study suggests that this BA.2 outbreak and the exceptionally high case-fatality rate in the ≥80 year-old age group (9.2%) could be attributed to the lack of protective immunity in the population, especially among the vulnerable older adults, and that ongoing sero-surveillance is essential.
UR - http://www.scopus.com/inward/record.url?scp=85132850937&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85132850937&partnerID=8YFLogxK
U2 - 10.1038/s41467-022-31395-0
DO - 10.1038/s41467-022-31395-0
M3 - Article
C2 - 35750868
AN - SCOPUS:85132850937
SN - 2041-1723
VL - 13
JO - Nature Communications
JF - Nature Communications
IS - 1
M1 - 3618
ER -