COVID-19's Fourth Wave: What You Need to Know Now

For an interactive version of this chart, visit CDC.gov.

So far more than 64 million Americans have been fully vaccinated, and about 110 million Americans have received at least one dose of a two-dose series, federal data show. What's more, the majority of Americans 65 and older — the population most affected by serious illness and death from the virus — have been vaccinated. “That's a big difference now,” compared to previous COVID-19 waves, Cash-Goldwasser says.

Variants could send cases soaring

That's not to say the current trends are less worrisome. Vaccinating the most vulnerable drives down hospitalizations and deaths, but it's important to note that less severe cases are not entirely harmless, Cash-Goldwasser points out. “Even in a mild infection, there is a risk of long COVID or some of these complications that we hear about.”

"Long COVID” is the term coined to describe lingering symptoms — fatigue, headaches, brain fog and shortness of breath, to name a few — that can persist weeks, sometimes months, after a coronavirus infection. A report from the Centers for Disease Control and Prevention (CDC) found that as many as 35 percent of people with mild cases of COVID-19 still felt its effects weeks after testing positive for the virus.

One difference at this stage in the pandemic that could drive up case counts, even as more Americans get vaccinated, is the continued spread of new virus variants, some of which are more contagious and potentially more lethal. CDC Director Rochelle Walensky recently announced that the B.1.1.7. variant, first identified in the United Kingdom, is “now the most common lineage circulating in the United States.” So far more than 16,000 reported COVID-19 cases have been caused by this variant, and spikes are occurring in a number of states, including Michigan, Minnesota, Florida, Colorado, California and Massachusetts, CDC data show.

Other variants are circulating in the U.S., and more could emerge. But there are ways to protect yourself from these concerning strains, and that's by following the same public health guidance that experts have been promoting all along: Wear a mask in public, keep a safe distance from others, wash your hands often and avoid crowded and poorly ventilated spaces. Health leaders are also encouraging people to get vaccinated when it's their turn.

"This is a good reminder to follow those infection prevention efforts as we work to vaccinate people,” says Saskia Popescu, an infectious disease epidemiologist and assistant professor at George Mason University's Schar School of Policy and Government.