Mix-and-match COVID vaccines trigger potent immune response

Abstract

accinating people with both the Oxford-AstraZeneca and the Pfizer-BioNTech COVID-19 vaccines produces a potent immune response against SARS-CoV-2, researchers conducting a study in Spain have found.Preliminary results from the trial of more than 600 people -announced in an online presentation on 18 May -are the first to show the benefits of combining different coronavirus vaccines (see go.nature.com/2s62qst).Because of safety concerns, several European countries are already recommending that some or all people who were given a first dose of the vaccine developed by the

COVID-19: Unmasking Emerging SARS-CoV-2 Variants, Vaccines and Therapeutic Strategies

“…Serum samples obtained after the second dose of the BBIBP-CorV vaccine (Sinopharm) or CoronaVac vaccine serum samples showed complete or partial loss of neutralization against B.1.351 [197]. Finally, randomized placebo-controlled clinical trials reported in press release by Novavax and Janssen companies in South Africa indicate significant decrease in the efficacy of their vaccines in places where the B.1.351 variant dominated [91,198]. Similarly, a clinical trial evaluating two-dose regimen of AZD1222 (AstraZeneca/Oxford vaccine) in South Africa did not show protection against mild to moderate COVID-19 due to B.1.351 variant [91,199].…”

“…Interestingly, a clinical trial with more than 600 people who already received first dose of the ChAdOx1 nCoV-19 (developed by Oxford-AstraZeneca, an adenovirus based vaccine) followed by a booster (eight weeks later) of BNT162b2 showed robust humoral response compared to single dose ChAdOx1 nCoV-19 vaccine. These antibodies were able to recognize and inactivate SARS-CoV-2 in laboratory tests [91]. Another mRNA vaccine, CVnCoV (developed by CureVac AG), effectively generates neutralizing antibodies against SARS-CoV-2 as observed in convalescent patient sera [92].…”

“…Finally, randomized placebo-controlled clinical trials reported in press release by Novavax and Janssen companies in South Africa indicate significant decrease in the efficacy of their vaccines in places where the B.1.351 variant dominated [91,198]. Similarly, a clinical trial evaluating two-dose regimen of AZD1222 (AstraZeneca/Oxford vaccine) in South Africa did not show protection against mild to moderate COVID-19 due to B.1.351 variant [91,199]. In Qatar, mass immunization campaigns have revealed that the estimated effectiveness of the Pfizer-BioNTech vaccine against the B.1.1.7 variant was 89.5% at 14 or more days after the second dose, while the effectiveness against infection with the B.1.351 variant was 75.0% [200].…”

Emerging issues related to COVID-19 vaccination in patients with cancer

“… Per applicable guidance as on 26 May 2021, vaccines are not interchangeable, and the same vaccine that was used for the prime dose should be administered for the booster shot. However, “mix-and-match” studies are ongoing, including priming with ChAdOx1 nCoV-19 and boosting with BNT162b2 [ 52 , 53 ], and such heterologous prime-boost combinations could be approved for use in the future. Even though COVID-19 vaccines currently have an emergency use authorization rather than full authorization, the US FDA has clarified that patients on clinical trials may receive COVID-19 vaccines, and this will not be considered a protocol deviation in studies that disallow the concurrent use of investigational agents [ 54 ].…”

“…Per applicable guidance as on 26 May 2021, vaccines are not interchangeable, and the same vaccine that was used for the prime dose should be administered for the booster shot. However, “mix-and-match” studies are ongoing, including priming with ChAdOx1 nCoV-19 and boosting with BNT162b2 [ 52 , 53 ], and such heterologous prime-boost combinations could be approved for use in the future.…”