It also comes at a time when much of the US has relaxed almost all Covid restrictions on the public and life has largely returned to normal. “Covid-19 is very clear that it is not over. We are seeing dramatic increases in the number of cases and hospitalizations in many places in the United States,” said Jason Salemi, associate professor of epidemiology at the University of South Florida College of Public Health. As the BA.5, one of Omicron’s subvariants, begins to hit the US, “we’re headed in a bad direction,” Salemi said. “We’ve seen it coming for a while … We’ve seen it go pretty much unabated.” More than one in three Americans live in a medium-risk county from Covid, and one in five are at high risk, according to the US Centers for Disease Control and Prevention (CDC). This is the highest percentage of the country facing risks since February, Salemi said. There are now more than 100,000 new confirmed cases of Covid every day in the US – a rate that has been fairly steady over the past six weeks. While cases in the northeast have slowed, increases are now affecting other parts of the country. There are many opportunities to reduce immunity and reduce vaccine protection without these booster doses to allow these new circulating variants with some perhaps more worrisome traits to do a little more damage Jason Salemi At the same time, hospitalizations have been rising steadily since the pandemic’s lowest point in April — though the rise hasn’t been as steep or peaked as high as previous waves. “The older you are, the more likely you are to be hospitalized,” Salemi said. “But hospitalizations are increasing for every age group.” Hospitalizations tend to lag behind cases by a few days. But a seemingly steady rate of cases with increasing hospitalizations means something else seems to be at play, experts said — possibly waning immunity in the face of a more contagious, immune-evasive and pathogenic variant. The virus is evolving to avoid the protection from infection offered by vaccination or recovery from a previous illness with Covid and also appears to be more contagious. The immune-evading properties of evolving variants make new waves more likely, says Tulio de Oliveira, director of the Center for Epidemic Response and Innovation at Stellenbosch University and head of the Network for Genomic Surveillance in South Africa. “BA.4 and 5 are potentially the variants that can break through immunity the easiest way,” he said. They are “really capable of reinfection”. In South Africa, BA.1 — the first micron variant — offered very little protection against contamination with BA.4 and BA.5, de Oliveira said. Antibodies generated by BA.1 infection do not protect against re-infection after two or three months, according to laboratory research. There are simple steps we can take to dramatically reduce the risks – not just to ourselves and our family, but to many of those members of our community who are most vulnerable Jason Salemi Infection with BA.2 seemed to offer some protection, possibly because this wave was more recent, he said. But while immunity to infection appears to be low, prior immunity is still resistant to serious outcomes such as hospitalization and death. Vaccinated and previously infected people “get BA.4 and BA.5 easily, but they will develop very little disease,” de Oliveira said. In a preprinting study in hamsters, the new variants appear to be much more virulent and pathogenic than previous omicron variants. But South Africa saw no more severity from BA.4 and 5 than during the other micron waves. This is because the severity of these variants depends on immunity levels in addition to their inherent properties. “Now [severity] it is a property not only of the variant itself, but of the variant and the population it encounters,” de Oliveira said. Even before this wave, around 95% of South Africans were estimated to have been protected by vaccination or previous bouts with Covid. “We believe that this hybrid immunity in South Africa is what has kept our BA.4 and BA.5 wave with very low hospitalizations and deaths,” said de Oliveira. Even if the variants are more pathogenic in the lab, high levels of immunity can help keep serious disease at bay. This is why staying informed about vaccination is key. “The first and second boosters are very important,” Salemi said. However, only 34% of eligible Americans – those over the age of 5 – have received booster doses as recommended by the CDC. While first-reinforcer intake was better among older Americans, the highest-risk age group, second-reinforcer intake was extremely low. “There’s a lot of opportunity for waning immunity and waning protection from the vaccine, without those boosters, to allow these new circulating variants with some maybe more worrisome traits to do a little more damage,” Salemi said. Declining immunity combined with a more immune variant means “you may start to see a rebound in some of these markers of serious disease.” Deaths in South Africa also remained low largely because hospitals were not overburdened. “When the BA.4 and BA.5 waves started, we had a completely empty ICU – so anyone who got sick could have good support,” de Oliveira said. “That will be the key in the US,” he said. “It’s very different if a new wave comes and the hospitals are already overwhelmed.” That’s one reason the Delta wave was so deadly, because it lingered for a long time and kept hospitals full, he said. Pockets of the U.S. with low levels of immunity — including those not recently vaccinated or who have not recovered from the virus — could see more severe disease. But places with high vaccination rates and recent increases will likely fare better when it comes to hospitalizations and deaths, he said. In South Africa, the wave came quickly and ended quickly too – but it had a significant economic impact, with people unable to work due to illness. To minimize the effects of an outbreak, including the risk of economic turmoil and long-term issues like lingering Covid, Americans need to “get the numbers down as fast as we can,” Salemi said. This includes taking the same measures that have been shown to help manage the virus in the past: vaccines, masks, distancing, ventilation, testing. “Please don’t think of mitigation as all or none,” Salemi said. “There are simple steps we can take to dramatically reduce the risks – not just to ourselves and our family, but to many of those members of our community who are most vulnerable.” As each infection offers new opportunities for the virus to evolve and escape immunity, scientists and officials around the world must continue to monitor it, de Oliveira said. “This virus has surprised us too many times.”
