What we know about COVID-19 seems to change by the minute.
It’s understandable, given the massive scale of the pandemic. More than 233 million cases have been confirmed around the world since tracking began. And even now — as we’re inching closer to two full years of living with the pandemic — the virus and ways to address it are still relatively new to the medical world, so researchers are learning as they go.
The amount of information out there about the coronavirus is dizzying. It’s hard to keep track of what’s known, what’s a myth and what guidance we should follow. That’s why HuffPost has rounded up five of the most important new things we learned about COVID-19 in September.
1. We finally learned who is eligible for boosters
After some pretty public and confusing back and forth, the Centers for Disease Control and Prevention and Food and Drug Administration both announced their official booster guidelines in September. They were pretty scaled back from what the Biden administration announced in August, when it suggested that all Americans would be eligible for boosters starting this fall.
Instead, here is who’s eligible for a third, booster dose of the Pfizer vaccine right now. (Federal regulators have not yet weighed in on a third dose of Moderna or a second dose of Johnson & Johnson):
If you’re 65 or older, or you live in a long-term care setting, and you received two doses of the Pfizer vaccine, you should receive a Pfizer booster.
If you’re 50-64 with an underlying medical condition, you should receive a Pfizer booster.
If you’re 18-49 with an underlying condition, you may receive a Pfizer booster.
And if you’re 18-64 working a job that puts you at increased risk of exposure and transmission, you may receive a Pfizer booster.
Despite confusion in the lead-up to the announcement, there does appear to have been a demand for a booster dose. In the first weekend after the new guidelines were released, roughly 400,000 booster doses were administered, the Biden administration said — and more than 1 million people have scheduled their third dose.
2. The Pfizer vaccine should be available to younger kids soon
In another big piece of news on the vaccine front, Pfizer released data in September suggesting that two low doses of its vaccine are safe and highly effective in children ages 5 to 11.
Pfizer has since submitted its data to the FDA and is expected to officially request authorization in a matter of weeks — though it’s unclear exactly how long the agency will take to review the data.
Still, some experts are hopeful that younger children will start rolling up their sleeves before Halloween.
3. Vaccines have more unexpected health benefits
The primary health benefit of the COVID-19 vaccines is that they’re very good at keeping people from getting really sick or dying from the virus.
But a new study published in September revealed an additional health perk: People who get vaccinated may experience improvements in their mental health.
After just one jab, people were less likely to show signs of moderate to severe depression, and even people who hadn’t been vaccinated yet, but who intended to get the jab, saw a boost in their overall mental well-being.
In recent years, experts and the general public have really come to better understand that mental health is every bit as important to overall well-being as physical health, and the pandemic has certainly placed people under profound stress. So the mental health benefit of vaccination is an additional bonus experts say we should not dismiss.
4. Getting vaccinated after a COVID-19 infection gives you a very good level of immunity
A study published in September examined an incident where the delta variant tore through a Texas prison, infecting three-quarters of the incarcerated people there — most of whom were fully vaccinated with Pfizer shots. But while the study clearly demonstrated that breakthrough cases can happen, particularly in high-risk settings where people spend a lot of time indoors together, it also offered some positive news.
Only one person who was vaccinated and who caught COVID-19 was hospitalized, showing once again that the vaccines largely prevent severe illness.
And the lowest rate of severe illness was among those who were fully vaccinated and who had also previously been infected with COVID-19. That’s why groups like the CDC have long recommended that people get vaccinated, even if they’ve already had COVID-19.
5. People who are unvaccinated are 10 times as likely to be hospitalized
Since delta became the dominant variant, experts have been scrambling to better understand how well our current vaccines hold up against breakthrough infections and serious illness. But new data published by the CDC in September showed that vaccines continue to prevent severe illness from COVID-19 — including from the virus’s delta variant.
Research pulled from real-world data on infections and outcomes after delta took over showed that people who are unvaccinated have more than 10 times the risk of being hospitalized and more than 10 times the risk of dying compared to those who are fully vaccinated. It’s just another reason for people who are eligible and who have not yet been vaccinated to get the shot.
Experts are still learning about COVID-19. The information in this story is what was known or available as of publication, but guidance can change as scientists discover more about the virus. Please check the Centers for Disease Control and Prevention for the most updated recommendations.