Effectiveness of homologous and heterologous booster doses for an inactivated SARS-CoV-2 vaccine: a large-scale prospective cohort study

COVID-19 vaccine booster strategy: striving for best practice

“…Two-dose vaccination regimens even with mRNA vaccines showed a rapid and pronounced loss of protection against symptomatic infection with the omicron variant 6 and for severe disease even before the surge of the omicron variant. 7 Because the results reported by Jara and colleagues 1 do not cover the omicron surge, we cannot estimate the effectiveness of the three-dose schedules in those settings. McMenamin and colleagues 8 analysed the data from Dec 31, 2021, to March 8, 2022, to estimate the vaccine effectiveness of BNT162b2 and CoronaVac vaccines covering the fifth wave of COVID-19 with omicron BA.2 lineage in Hong Kong.…”

“…In The Lancet Global Health , Alejandro Jara and colleagues 1 report the effectiveness of CoronaVac (Sinovac Biotech), AZD1222 (Oxford-AstraZeneca), and BNT162b2 (Pfizer-BioNTech) boosters after the completion of a primary schedule with two doses of CoronaVac. The results are based on the analyses of real-world data from a dataset gathered from a single centralised immunisation registry of nearly 11·2 million individuals aged 16 years or older, representing 80% of the Chilean population.…”

“…Although the study by Jara and colleagues 1 supports a so-called mix-and-match approach, the optimum strategies and dosing intervals to provide maximum benefit in the context of the SARS-CoV-2 variants in circulation need to be defined. Zeng and colleagues 3 reported that neutralising antibody titres induced by two doses of CoronaVac declined to near or below the lower limit of seropositivity after 6 months; however, a third dose given 8 months after the second dose led to a strong boost in immune response.…”

“…The results of the study by Jara and colleagues 1 provide insights to policy makers on how to manage the booster dose strategy after two doses of CoronaVac vaccination. It is now clear that, in a world where vaccine equity is a utopia, scientists can only strive for how to best use the available vaccines to reach for a maximum attainable benefit.…”

Covid-19: Mix and match booster vaccination approach offers best protection, study reports

“…Using a different covid-19 vaccine for the third “booster” dose than was used for the initial two doses provides a higher level of protection, a study has found 1…”