Summary Background: Multimorbidity is a prevalent risk factor for COVID-19-related complications and death. We sought to evaluate the association of homologous booster vaccination using BNT162b2 (Pfizer-BioNTech) or CoronaVac (Sinovac) with COVID-19-related deaths among people with multimorbidity during the initial Omicron wave of the COVID-19 pandemic. Methods: Using routine clinical records from public health facilities in Hong Kong, we conducted a territory-wide retrospective cohort study comparing people aged 18 years or older with 2 or more chronic conditions who received a homologous booster dose ( third) with those who received only 2 doses, between November 11, 2021 and March 31, 2022. The primary outcome was death related to COVID-19. Results: We included 120,724 BNT162b2 recipients (including 87,289 who received a booster), followed for a median of 34 (interquartile range [IQR] 20–63) days, and 127,318 CoronaVac recipients (including 94,977 who received a booster), followed for a median of 38 (IQR 22-77) days. Among BNT162b2 recipients, people who received the booster vaccine had fewer COVID-19-related deaths than those who received 2 doses (5 vs. 34, incidence rate 1.3 vs. 23.4 per million person-days, weighted incidence rate ratio [IRR] 0.05, 95% confidence interval [CI] 0.02-0.16). We observed similar results among recipients of the CoronaVac booster vaccine compared to those who received only 2 doses (26 vs. 88, incidence rate of 5.3 vs. 53.1 per million person-days, weighted IRR of 0 .08, 95% CI 0.05 to 0.12). Interpretation: Among people with multimorbidity, booster vaccination with BNT162b2 or CoronaVac was associated with more than 90% reductions in COVID-19-related mortality rates compared with just 2 doses. These results highlight the crucial role of booster vaccination in protecting vulnerable populations as the COVID-19 pandemic continues to evolve. |
Weighted cumulative incidence of COVID-19-related deaths after (A) BNT162b2 or (B) booster vaccine or 2 doses of CoronaVac, with 95% confidence intervals (CI) represented by the shaded area. The index date is operationalized as the date of the booster vaccination or the coincident pseudoindex date for those who received 2 doses of the vaccine.
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A booster (third) dose of a SARS-CoV-2 vaccine was associated with a 90% reduction in deaths in people with multiple health conditions compared to 2 doses, according to a new Hong Kong study published in CMAJ ( Canadian Medical Association Journal ).
"We found a substantially reduced risk of COVID-19-related death in adults with multimorbidity who received a homologous booster dose of BNT162b2, an mRNA vaccine, or CoronaVac, an inactivated whole virus vaccine," writes Dr. Esther Chan, Li Ka Shing Faculty of Medicine, University of Hong Kong and Health Data Discovery Laboratory, Hong Kong, with co-authors. "These results support the effectiveness of booster doses of vaccines from 2 different technology platforms in reducing mortality among people with multimorbidity amid the Omicron epidemic."
When the Omicron variant (BA.2) epidemic hit Hong Kong in late 2021, the city reported the highest COVID-19 death rate worldwide relative to its population of 7.5 million people. . Since November 11, 2021, older people, healthcare professionals and other priority groups were able to receive a booster dose of the BNT162b2 mRNA vaccine (Fosun-BioNTech, equivalent to Pfizer-BioNTech outside China) or CoronaVac (Sinovac ). As of January 1, 2022, everyone else was eligible, resulting in more than 3 million people receiving booster doses in the first 4 months of 2022.
"Our findings suggest that this massive and timely public health measure has played a critical role in reducing the mortality rate amid the epidemic, especially among people living with multimorbidity," writes Francisco Lai, first author and scientist. from Li Ka Shing Faculty. of Medicine, The University of Hong Kong and Laboratory of Data Discovery for Health, Hong Kong, with co-authors.
Researchers compared data from people 18 years or older with 2 or more chronic conditions, such as high blood pressure, diabetes, and chronic kidney disease, who received a booster (third) dose between November 11, 2021 and March 31 of 2022, compared to people who received only 2 doses. The study included 120,724 recipients of the Pfizer-BioNTech vaccine (87,289 who received a booster) and 127,318 recipients of CoronaVac (94,977 who received a booster). There were more deaths among CoronaVac recipients than among Pfizer-BioNTech recipients.
The study findings "highlight the potential benefit of booster vaccination, specifically in vulnerable populations living with multimorbidity, and support the recent focus on older people and those with chronic conditions for future booster doses of SARS vaccines." CoV-2 beyond the first booster."
The strong results will contribute to the evidence base that receiving a booster provides strong protection against death from COVID-19.
"As the data on SARS-CoV-2 vaccination records used for this study were provided by the sole vaccine implementation operator in Hong Kong, with a unified registration system and with linked clinical records provided by a health care provider territory, our data must be highly reliable and representative," the authors conclude.
