President Joe Biden has painted a bright picture for the coming Fourth of July holiday, claiming all Americans will have access to a COVID-19 vaccine by May 1. Assuming most people accept their shots, and the vaccination rate continues at its current pace, the restrictive cloud hanging over the country could finally lift by summer.
But experts behind the science aren’t planning their backyard barbecues just yet.
Reaching that long-awaited herd immunity – the place where enough Americans are vaccinated that their collective immunity protects unvaccinated citizens from disease – hinges on many factors. Mishandled mandates, vaccine naysayers and virus variants top the concerns, along with COVID-19’s track record of surprises.
Easing of mandates ignites worries
“Even though transmission and case rates have come down a lot since the end of December and beginning of January, we are still at the same level that we were back in October,” said Thomas Campbell, MD, an infectious disease expert at the University of Colorado School of Medicine on the CU Anschutz Medical Campus.
“Why should we be doing anything differently now than we were doing in October?” he asked, referring to the abandonment of mask mandates and other COVID-19 restrictions in Texas and Mississippi. “I think that is reckless.”
Since then, Gov. Jared Polis announced plans to ease some restrictions in Colorado. Planned actions include reopening bars, lifting gathering size limits, easing mask mandates and relinquishing public health orders to local governments in the coming weeks.
With just 14% of the U.S. population fully vaccinated, and the emergence of more transmissible variant viruses in the country, a current trend by some governors of loosening mandates could sabotage the president’s stated goals, sending cases skyrocketing again, Campbell and many experts warn.
“That’s the biggest fear everybody has,” said Ross Kedl, PhD, a vaccine expert and professor in the Department of Immunology & Microbiology, of cases trending back up because of lifted mandates. “But, oddly enough, I’m also extremely concerned about the second possibility – that it actually works.”
Predictions tough with volatile factors
Many experts say the country must reach a 70% or 80% vaccination rate for herd immunity before normalcy can return, a goal Biden predicts the nation will hit by its birthday. “That’s the general benchmark for protection in a population, about 80%,” said Campbell, who suspects the president’s prediction is too early.
But when monitoring transmission suppression from vaccines, there’s a more important number to watch, Kedl said. “The ratio of vaccinations per cases actually better informs how quickly the caseload will drop and how significantly society can change,” he said, noting the ratio is currently about 40 to one.
“Why should we be doing anything differently now than we were doing in October? I think that is reckless.” – Thomas Campbell, MD
“That’s a more significant number than the absolute number of vaccinated people,” he said. “You always find a significant impact on transmission far before you see anything approaching herd immunity, which just sustains it at as much of a suppressed level as possible.”
Predicting that tipping point is only weeks away, Kedl said there’s a chance that opening businesses won’t backfire and cause an explosion in cases, provided the vaccination rollout continues at a good pace.
“I think it may be less remote than a lot of people say. If that’s the case, great for the country, but once again, the authorities have lost a lot of credibility,” said Kedl, who has continued to sound the alarm about poor messaging during the pandemic, worried about the loss of faith in medical science.
Two wildcards: Naysayers and youth
Vaccine refusers and children could also thwart the president’s summer goal, Campbell said. Surveys suggest at least 20% of Americans will refuse the vaccine, a number that could be much higher, and COVID-19 vaccines are not approved for youth.
While youth trials are ongoing, Campbell, who has directed adult vaccine trials on the CU Anschutz campus during the pandemic, does not believe approval for children and teens will come by July. He says fall approval would be more likely for this group, which accounts for about 25% of the population.
Add youth and vaccine decliners together, and that represents at least 45% of the population, Campbell said. “So, I think there is a disconnect in statements that say we would be at 80% population protection by the summer. I don’t think that’s going to happen. That’s still a lot of petri dishes for the virus to continue to spread and for the variants to continue to spread.”
Kedl worries that politics, anti-vaxxers, and undercurrents about vaccine safety could push the naysayer number closer to 40%, further complicating the fight against COVID.
Emerging variants raise red flags
Circulating variants of the virus, some more infectious than the original SARS-CoV-2, deal another wildcard when it comes to summer’s outlook, the experts say.
“There are three variants of concern right now,” Campbell said, referring to variants emerging from Brazil (P.1), South Africa (B.1.351) and the United Kingdom (B.1.1.7.).While the UK variant has been detected in the United States, it appears the current vaccines and likely previous COVID-19 infection protect against the mutated version, Campbell said. However, early studies suggest natural immunity fails to protect against the other two variants, he said.
One study involved about 5,000 South Africans randomized into vaccinated and placebo groups. About 30% of participants in the placebo group had prior COVID-19. “They had the same infection rate with the South African variant as the people who had no antibodies detected at baseline.” This finding indicates that recovery from natural infection does not protect against re-infection with the B.1.351 variant.
The P.1 variant arose in a Brazilian city of about 2 million people that had undergone a big wave of COVID-19 in the summer of 2020, infecting about 70% of the population, Campbell said. “Despite that, when the new P.1. variant emerged in December and caused a massive new surge of infections, people who had been previously infected appeared to have little or no protection.”
“Even though recovery from natural infection provides no protection against the B.1.351 and P.1 variants, available data suggest that the current vaccines give reduced but good protection against B.1.351. We don’t yet know whether vaccines protect against P.1,” Campbell said.
Summer 2019? No. But better than 2020
The good news: The current vaccines appear to provide some protection against the variants, including a reduced risk of severe disease. Moreover, both Moderna and Pfizer are working on booster vaccines that cover the mutations that should be ready by fall for an even stronger defense.
Getting a COVID-19 booster shot every year or two might be in our future, Kedl said, reminding that virus mutation is normal. “There is no evidence that these variants are multi-headed monsters for whom we have no defense.”
While little surrounding COVID-19 has ever been certain, and the picture come summer could range widely, both scientists say there is solid reason to believe it will be better.
“I don’t think it’s going to be back to normal,” Campbell said. “But the good news is you can do more if you are vaccinated, and the summer will probably be better than summer of 2020. It just won’t be summer 2019.”
“There is no evidence that these variants are a multi-headed monster for whom we have no defense.” – Ross Kedl, PhD
