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
PY - 2022
Y1 - 2022
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 - https://www.scopus.com/record/pubmetrics.uri?eid=2-s2.0-85132850937&origin=recordpage
U2 - 10.1038/s41467-022-31395-0
DO - 10.1038/s41467-022-31395-0
M3 - RGC 21 - Publication in refereed journal
C2 - 35750868
SN - 2041-1723
VL - 13
JO - Nature Communications
JF - Nature Communications
M1 - 3618
ER -
