Real-world effectiveness of homologous and heterologous BNT162b2, CoronaVac, and AZD1222 booster vaccination against Delta and Omicron SARS-CoV-2 infection

Abstract

Given emerging evidence of immune escape in the SARS-CoV-2 Omicron viral variant, and its dominance, effectiveness of heterologous and homologous boosting schedules commonly used in low-to-middle income countries needs to be re-evaluated. We conducted a test-negative design using consolidated national administrative data in Malaysia to compare the effectiveness of homologous and heterologous BNT162b2, CoronaVac, and AZD1222 booster vaccination against SARS-CoV-2 infection in predominant-Delta and predominant-Omicron periods. Across both periods, homologous CoronaVac and AZD1222 boosting demonstrated lower effectiveness than heterologous boosting for CoronaVac and AZD1222 primary vaccination recipients and homologous BNT162b2 boosting. Broadly, marginal effectiveness was smaller by 40–50 percentage points in the Omicron period than the Delta period. Without effective and accessible second-generation vaccines, heterologous boosting using BNT162b2 for inactivated and vectored primary vaccination recipients is preferred.

Kinetics of the Neutralizing and Spike SARS-CoV-2 Antibodies following the Sinovac Inactivated Virus Vaccine Compared to the Pfizer mRNA Vaccine in Singapore

“…Thus, inactivated vaccines do induce a rise in nucleocapsid antibodies [ 35 ] and prevents its use in the diagnosis of asymptomatic/pauci-symptomatic post-vaccination infection as well as the identification of previous exposure to COVID-19. The nucleocapsid antibodies developed in response to inactivated vaccines may have a theoretical benefit against the Omicron strain; however, real-world evidence [ 36 ] has shown that mRNA vaccines, even when used in a heterologous dosing regimen, provided greater protection against COVID-19 infection during waves of Omicron predominance. Although we were able to assess S-Ab and N-Ab responses to vaccines, we were unable to assess the development of memory B cells in response to inactivated vaccines.…”

Epidemiological characteristics and transmission dynamics of the outbreak caused by the SARS-CoV-2 Omicron variant in Shanghai, China: A descriptive study

“…Compared to Western countries, the population in Shanghai was mostly vaccinated with domestically-developed inactivated vaccines, which had relatively lower effectiveness in preventing SARS-CoV-2 infections due to their lower antibody-neutralizing responses compared to mRNA vaccines. 9 , 10 In addition, the vaccination coverage was highest in the young population (100.0% in individuals aged between 12 and 17 years had completed the primary vaccine schedule as of March 2022) 11 and lowest in the elderly (only 62.0% in individuals aged 60 years or older had completed the primary schedule as of April 2022). 12 Most importantly, a wide range of NPIs were adopted to achieve outbreak containment, in contrast to the mitigation strategy adopted by most regions outside mainland China.…”

Epidemiological characteristics and transmission dynamics of the outbreak caused by the SARS-CoV-2 Omicron variant in Shanghai, China: a descriptive study

“…Shanghai is one of the most populous and economically advanced metropolises in China, with a population of nearly 25 million 8 and unique features compared to other areas in mainland China and abroad. The population in Shanghai was mostly vaccinated with domestically-developed inactivated vaccines, which had relatively lower effectiveness in preventing SARS-CoV-2 infections due to their lower antibody-neutralizing responses compared to mRNA vaccines 9,10 . In addition, the vaccination coverage was highest in the young population (100.0% in individuals aged between 12 and 17 years had completed the primary vaccine schedule as of March 2022) 11 and lowest in the elderly (only 62.0% in individuals aged 60 years or older had completed the primary schedule as of April 2022).…”