MIAMI — Florida is barely over the omicron wave that caused unprecedented numbers of COVID-19 cases and overwhelmed hospital systems with infected patients and staff. But a new subvariant of the coronavirus has already emerged and appears to be more contagious, raising concern that another pandemic wave of infections is on the way.
Though COVID-19 cases are falling in Florida and most of the country, epidemiologist and public health experts warn that the omicron subvariant called BA.2 is driving an increase in cases in Western Europe and elsewhere and may follow a familiar pattern with infections rising in the United States.
There are still many unknowns about the potential for BA.2 to spark another surge, including the level of baseline immunity from vaccination and prior infection, and the relaxation of masking, social distancing and other measures to mitigate transmission of the virus.
To understand what lies ahead, the Miami Herald interviewed public health experts about BA.2 and its potential to throw communities into disarray once again.
What do we know about BA.2?
The subvariant BA.2 was first identified in November when scientists discovered omicron. But scientists began to find BA.2 in larger proportions in January, including in Miami. BA.2 now accounts for more than half of cases in the Northeast and about one in five cases in the Southeast, including Florida.
BA.2 is about 50% to 60% more contagious than the original omicron variant, called BA.1, said Amber D’Souza, an epidemiologist and professor at Johns Hopkins University’s Bloomberg School of Public Health. D’Souza said BA.2 appears to cause mild disease, like omicron, but that some small portion of the population is likely to experience severe illness and hospitalization.
Does prior infection with omicron protect against BA.2?
It does appear that prior infection with omicron will protect against BA.2, said Stephen Kissler, a researcher in the Department of Immunology and Infectious Diseases at Harvard T.H. Chan School of Public Health. Vaccination and prior infection appears to confer strong protection.
However, it is not clear how long immunity lasts, and for those with prior infections it can be difficult to tell when they got infected and with what virus.
“One of the things that seems to be the case is that repeated exposures to SARS-CoV-2, especially through vaccination but also through previous infection, enhance your immunity. And they enhance not only the amount of immunity that you have but also the breadth of the immunity that you have, your ability to identify other sorts of viruses.”
Do vaccines/boosters protect against BA.2?
The vaccines and a third dose, called a booster, appear to protect against BA.2. Even if they do not prevent infection as well as they did against omicron, they do protect against severe disease and death from BA.2, said D’Souza.
“The initial data that we have suggests that we do have protection from immunization and previous infection to this variant. That protection is not as good as protection against the original [omicron] variant but it is still good against severe disease,” D’Souza said.
Will there be a BA.2 wave in the United States, South Florida?
No one knows yet, but we will likely see an increase in cases as more communities lift mask ordinances and other mitigation measures. And cases have been rising in Western Europe, where COVID-19 surges have preceded waves in the United States often in the past two years.
Nationally, BA.2 accounts for about 35% of cases, with rates varying by region, according to data on variant proportions published by the Centers for Disease Control and Prevention.
In South Florida, scientists tracking variants in the community are finding increasing numbers of BA.2, said David Andrews, a physician and associate professor in the Department of Pathology and Laboratory Medicine at the University of Miami’s Miller School of Medicine. “We’re starting to see it mirror the national trends in terms of percentage and prevalence,” Andrews said.
What precautions should I take in the coming weeks?
Epidemiologists and infectious disease specialists recommend that you check CDC and local health department data to assess the level of COVID-19 transmission in your community and take appropriate mitigation measures to reduce your risk of getting infected.
With cases still declining, many people are no longer wearing masks, said Anna Durbin, an infectious disease specialist and director of the Center for Immunization Research at Johns Hopkins Bloomberg School of Public Health.
“I don’t mask when I go into buildings. I go to restaurants. I’ve been eating out,” Durbin said. “When I travel, particularly because I’m planning a trip to Europe next week, I probably will wear a mask because rates are higher where I’m going. It really is situational dependent.”