COVID-19 vaccines authorized in US appear to be 'very protective' against variants

The emergence of SARS-CoV-2 variants worldwide has led to concern and confusion among the general public.

Recently, South Africa halted its rollout of the AstraZeneca-Oxford COVID-19 vaccine after preliminary data showed the vaccine provided limited protection against the country’s dominant B.1.351 variant. This has drawn concern that COVID-19 vaccines may not protect against the emerging SARS-CoV-2 variants.

During a press briefing, Gigi Gronvall, PhD, an immunologist and associate professor in the department of environmental health and engineering at John Hopkins Bloomberg School of Public Health, said that “it’s pretty normal for viruses to mutate like this — almost all viruses do.”

What are variants?

In a paper recently published in JAMA, Anthony S. Fauci, MD, director of the National Institutes of Allergy and Infectious Disease, and colleagues explained that variants form when mutations are selected through multiple rounds of viral replication.

“If the sequence variation produces a virus with distinctly different phenotypic characteristics, the variant is co-termed a strain,” they wrote. “When through genetic sequencing and phylogenetic analysis a new variant is detected as a distinct branch on a phylogenetic tree, a new lineage is born.”

Notable variants of SARS-CoV-2, they said, include B.1.1.1.7, which was first detected in the United Kingdom in October 2020. The strain appears to be more infectious and some studies have suggested that it is associated with a 30% increased risk for death.

The B.1.351 variant, they said, has two of the same mutations as B.1.1.1.7, which indicate that it has a “high potential for transmission.” However, they wrote that there is currently no data to suggest that there is an elevated risk for death associated with the variant.

Andy Pekosz, PhD, a virologist, professor and vice chair of the department of molecular microbiology and immunology at the Bloomberg School of Public Health and codirector of the Johns Hopkins Center of Excellence for Influenza Research and Surveillance, said that while some variants are more concerning than others, “it’s really important to keep track of all the changes that are accumulating in this virus because we never know when an important mutation will occur.”

He said that viruses often mutate, and most of these mutations are bad for the virus itself and disappear quickly. However, the mutations that remain usually do not affect the characteristics of the virus in humans.

Very rarely do the mutations give the virus an “advantage,” but it’s important to track the variants to determine which mutations have changed the properties of the virus, Pekosz said.

“We talk a lot about virus sequencing, but it’s also important to follow things like case numbers, disease severity and changes in populations that are being infected, because all of these things have signaled that the virus has mutated in a way that has changed its properties,” Pekosz said.

What still works?

During the press briefing, Gronvall said these variants are not “magic,” and “a lot of the things that we’ve been doing throughout this pandemic will continue to work when it comes to these variants.” For instance, masking and ventilation will still work against the variants.

Diagnostic tests are also effective with these variants, Gronvall said, explaining that “almost all the tests that are on the market should still be able to detect if there is an infection — they’re not going to be spurious false-negative results.”

Nevertheless, she noted that the FDA is monitoring this issue and will notify manufacturers and the public about any concerns with diagnostic tests and COVID-19 variants.

Gronvall said that vaccines with emergency use authorization in the United States — both the Moderna and Pfizer vaccines — appear to be “very protective” against COVID-19 variants.

Fauci and colleagues wrote that currently, interim data on the Johnson & Johnson vaccine suggested that the vaccine was 72% effective against COVID-19 in the U.S., 66% effective in Brazil and 57% effective in South Africa. They also said that data from the Novavax vaccine showed that it was 89% effective in the U.K. and 60% effective in South Africa. Viral sequence data indicate that the B.1.351 strain was responsible for most infections in South Africa during that time. However, while vaccine efficacy appeared to be lower in South Africa, the Johnson & Johnson vaccine was still 85% effective in preventing severe COVID-19 illness.

Monica Gandhi, MD, MPH, professor of medicine and associate chief of the division of HIV, infectious diseases and global medicine at the University of California, San Francisco, told Healio Primary Care that she is “very optimistic” about the efficacy of current COVID-19 vaccines, even against the variants. Her optimism is based on the high level of efficacy of the current vaccines for preventing severe disease, even in trial locations where these variants were circulating.

“I’m really heartened that T-cell response, generated with vaccines, likely will be protective for severe disease against all of the variants that we have circulating now,” she said.

The emergence of COVID-19 variants should not delay vaccinations, according to Gandhi. Instead, it is as important as ever to distribute COVID-19 vaccines. If enough people are “somewhat protected” against the virus, transmission “will slow down,” she said.

“The best way to get through these variants is to push through with vaccination, because even if there is slightly less efficacy of the vaccines for mild disease with variants — disease which you may not have even been aware of, normally — the efficacy of these vaccines against severe disease, even with variants, is what’s necessary to protect an individual,” Gandhi said.

Therefore, physicians should encourage patients to get the vaccine as soon as they are eligible, Gandhi said, in addition to reminding them to continue practicing infection prevention measures like masking and physical distancing, because that will continue to prevent further replication of the virus and prevent the spread of variants or the development of new variants.

Looking ahead

When asked how well the vaccines prevent transmission of SARS-CoV-2 and its variants, Gronvall said that vaccination is not a “bulletproof vest.”

Current evidence, she said, shows that people who become infected despite vaccination appear to have a lower viral load than those with no immunity, and that should help to reduce transmission.

“That’s why people are still recommending that if you’re going to be around unvaccinated people, to still wear a mask and to still take these precautions until community transmission is down so that you’re not encountering the virus and not having the potential to spread it to somebody else,” she said.

Gandhi stressed that the emergence of COVID-19 variants should not limit the ability of fully vaccinated individuals “to feel safe” and be more active. Still, “society will not collapse into normalcy yet,” she said.

“There is still going to be the requirement of masks and distancing for everyone out in public because, again, you don’t know that everyone who’s next to you is vaccinated,” she said.

References:

Mascola JR, et al. JAMA. 2021;doi:10.1001/jama.2021.2088.

Press Briefing