Current COVID-19 Vaccines Proving Efficacy Against New Variants
Newly-published studies suggest currently authorized COVID-19 vaccines may be effective for protecting against new and emerging variants of the novel coronavirus, while booster doses of these vaccines may improve the overall efficiencies of these immunizations at combating these variants.
A study conducted in Israel shows that fully vaccinated patients with the Pfizer/BioNTech's vaccine have much better protection after the recommended two doses versus just a single one. The study, published in the journal Lancet, shows this vaccine was 95.3% effective at protecting against infection, severe illness and death. Additionally, the vaccine was 96.7% effective at protecting against death within seven days following the second dose.
The authors wrote: "Two doses of BNT162b2 are highly effective across all age groups in preventing symptomatic and asymptomatic SARS-CoV-2 infections and COVID-19-related hospitalizations, severe disease, and death, including those caused by the B.1.1.7 SARS-CoV-2 variant.”
While the British COVID-19 variant B.1.1.7 is now circulating in Israel, this variant was not causing significant infections in the country at the time of the study, so the investigators were unable to determine whether two doses of the Pfizer/BioNtech vaccine was protective against this strain.
A separate study published in the New England Journal of Medicine also evaluated the Pfizer vaccine in a population in the Gulf state of Qatar where COVID-19 variants B.1.351 and B.1.1.7 were present.
According to the researchers, the estimated efficacy of the Pfizer vaccine against COVID-19 infection with the B.1.1.7 variant was approximately 89.5% at two weeks or more following the second dose. In addition, the vaccine’s efficacy against the B.1.351 variant was about 75% following the second immunization.
Given that many of the new variants circulating worldwide are developing mutations that facilitate viral evasion of the immune system, manufacturers are rising to meet the demand for new vaccine formulations that could combat this worrying trend.
Reportedly, the new mRNA vaccines from Pfizer and Moderna make the development and testing of these new formulations much more accessible than other types of vaccines since researchers and scientists can easily modify the genetic sequences that form the basis of these mRNA products.
Moderna announced Wednesday that a booster shot comprising a half dose of its authorized vaccine could help boost the immune response against SARS-CoV-2 variants B.1.351 and P.1. The company also said that a booster dose of its vaccine designed to match B.1.351 also demonstrated an even higher efficacy.
In the most recent testing series, Moderna examined booster doses of its current vaccine or a new formulation designed to fight against B.1.351. The Phase II study included 40 people who had received vaccination approximately six to eight months before receiving the booster shots. According to blood tests, study participants demonstrated low pre-booster antibody responses against both the B.1.351 and the P.1 variants.
But just two weeks following the booster shot, the antibody levels of these participants had increased against the wild-type coronavirus, which represents the most commonly reported virus around the globe. The antibody responses also rose against the B.1.351 and P.1 variants. Overall, the severity of the adverse events reported throughout the study was generally mild or moderate.
"We are encouraged by these new data, which reinforce our confidence that our booster strategy should be protective against these newly detected variants,” said Moderna’s CEO Stéphane Bancel in a statement. “The strong and rapid boost in titers to levels above primary vaccination also clearly demonstrates the ability of mRNA-1273 to induce immune memory.”
Following the positive findings from this study, Moderna submitted the data to a pre-print server journal and plans on publishing it in a peer-reviewed journal once it gathers additional study data.
Novavax also recently found its COVID-19 vaccine protects against B.1.351. In the NEJM study, the vaccine maker confirmed that its vaccine was approximately 49% effective against the South African COVID-19 variant in adults irrespective of HIV status and 60% effective in adult patients without HIV. A new analysis published Wednesday showed the vaccine was 51% effective against South African variant-induced infections in individuals who were HIV negative and 43% effective against the variant in HIV-positive people.
Updated study findings were released by Novavax back in March – these findings indicated the vaccine reduced the risk of symptomatic infection by up to 55% in HIV-negative adults. Currently, Novavax has refrained from asking the U.S. Food and Drug Administration to authorize its vaccine for emergency use.