MONDAY, May 17, 2021 (HealthDay News) -- Participants receiving heterologous prime and boost doses of COVID-19 vaccines have an increase in systemic reactogenicity after the boost dose compared with those receiving homologous vaccine schedules, according to a research letter published online May 12 in The Lancet.
Robert H. Shaw, M.B.B.S., from the University of Oxford in the United Kingdom, and colleagues present the initial reactogenicity and safety data for the Com-COV study comparing all four prime-boost permutations of the ChAd and BNT vaccines, both at 28- and 84-day prime-boost intervals. Data were included for 463 participants in the 28-day prime-boost interval group.
The researchers found that compared with their homologous counterparts, both heterologous vaccine schedules induced greater systemic reactogenicity following the boost dose, with feverishness reported by 34 percent of those receiving ChAd for prime and BNT for boost versus 10 percent of those receiving ChAd for prime and boost, and for 41 percent of those receiving BNT for prime and ChAd for boost versus 21 percent of those receiving BNT for prime and boost. For chills, fatigue, headache, joint pain, malaise, and muscle ache, similar increases were observed. No hospitalizations occurred due to solicited symptoms; most of the increase in reactogenicity occurred in the 48 hours after immunization. Hematology and biochemistry profiles were similar for heterologous and homologous vaccine schedules; at day 7 after the boost dose, no thrombocytopenia occurred in any group.
"Importantly, there are no safety concerns or signals, and this does not tell us if the immune response will be affected," a coauthor said in a statement. "We hope to report these data in the coming months."
One author disclosed financial ties to vaccine manufacturers, including AstraZeneca, GlaxoSmithKline, Pfizer, Novavax, Janssen, Medimmune, and MCM vaccines.