What we know about COVID-19 seems to change by the minute.
It’s understandable, given the massive scale of the global pandemic. Right now, there are more than 63 million known cases around the world and counting. The virus is also relatively new to the medical world, so researchers are learning as they go.
The amount of information out there 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 we’ve rounded up five of the most important new things we learned about COVID-19 in November:
1. Vaccines could arrive by the end of 2020.
November was a remarkable month in the race to develop a COVID-19 vaccine. Drug maker Pfizer announced that the vaccine it is developing is more than 90% effective, and it now seems possible that around 6 million doses could be available in the United States by mid-December.
Moderna announced similarly encouraging results, releasing data that suggests its vaccine is 94% effective. The company asked regulatory bodies in the U.S. and Europe — including the FDA — to allow emergency use of its vaccine. That means some Americans could receive the vaccine as soon as Dec. 21.
Those breakthroughs were exciting for several reasons, one of which is that, from a scientific standpoint, both vaccines are just kind of ... remarkable. They rely on a pretty new type of technology called ”messenger RNA” or “mRNA” vaccines.
As the Centers for Disease Control and Prevention explains: “To trigger an immune response, many vaccines put a weakened or inactivated germ into our bodies. Not mRNA vaccines. Instead, they teach our cells how to make a protein — or even just a piece of a protein — that triggers an immune response inside our bodies.” In turn, that immune response produces antibodies that protect against COVID-19 infection.
Of course, vaccine distribution is going to be extremely challenging, particularly because mRNA vaccines need to be handled and stored in a very specific way. (The Pfizer vaccine, for example, must be kept at -94 degrees Fahrenheit.) There are questions about production capacity, about how states plan to distribute the vaccine (or vaccines, as these will require two doses) and who is considered highest priority. Experts are predicting that the earliest a vaccine will be widely available to most Americans is in April — and likely later for kids.
2. Restaurants and gyms may be the biggest drivers of COVID-19 infection.
As we anxiously await a vaccine, COVID-19 cases around the U.S. continue to soar. A new model, published in the journal Nature last month, pointed to what may well be the biggest culprits: cafes, restaurants and gyms.
The model relied on mobile phone data from 10 major U.S. cities, and the researchers say they were “able to faithfully estimate the contact network between 100 million people for every hour of the day.”
Their model corroborated what has been suggested in several other studies: Indoor venues, like restaurants and gyms, are major drivers of infection and may be significantly contributing to outbreaks in various areas.
That’s important data to have in mind as we navigate this winter, both at a policy level (as regulators decide what to close, what to cap and when) and at a personal level (as all of us decide what activities to partake in indoors).
However, the experts also caution against reading too much into the findings as the model relied on data from last spring, when our collective mask-wearing habits were very different. For example, eating in a restaurant now may be less risky than it was in March and April now that mask mandates are widely in place.
There are also other areas, like long-term care facilities and prisons, that are a leading source of spread, according to a November report from The New York Times. Finally, current evidence suggests that small gatherings among friends and family may also drive COVID-19 infections. So the Nature study’s findings are not a definitive list of where COVID-19 mainly spreads.
3. You’re most infectious with COVID-19 within five days of developing symptoms.
A study published in the journal the Lancet in November offered some much-needed clarity about when people who have COVID-19 are at their most infectious. The research found that the viral load of SARS-CoV-2 (which is a measure of how much virus is detected in the body at a given time) is highest from the time symptoms occur until about five days after.
And that period of high infectiousness is likely shorter for people who are largely symptom-free.
The findings are important, the study authors say, because they point to the need for people to isolate immediately when they notice any symptoms, even if those symptoms are relatively mild.
4. Our current methods for broad COVID-19 screening are ... not great.
Shortly before millions of Americans traveled for the Thanksgiving holiday, the CDC issued a pretty concerning report that concluded its enhanced screening program for people at U.S. airports had a very low case detection rate. “The program identified about one case per 85,000 travelers screened,” CNN reported,
There are several reasons why the program didn’t work all that well. Perhaps the biggest is that many people who have COVID-19 are asymptomatic, or they have symptoms that wouldn’t be caught with a temperature check and questionnaire about symptoms and exposure, which is what the CDC relied on.
The findings make plain that, despite our best efforts, there is no getting around the fact that travel increases the risk of getting and spreading COVID-19. It remains to be seen what the fallout will be from Thanksgiving travel, but there’s reason to believe much of the country will hit record highs in case counts.
The CDC report also suggests that temperature checks, which are used in places like schools, restaurants and stores as a supposed preventive measure, are truly of pretty limited value.
5. Masks protect the wearer from COVID-19, not just others.
OK yes, this is one we’ve known for a while now. But given that mask compliance continues to be an issue (1 in 4 Americans still do not support mask requirements for people out in public), the CDC made headlines when it issued a new scientific brief on face masks last month. The brief emphasized that masks don’t just protect others — they also protect the individual wearing them.
As the report explains, experts now know that multi-layer cloth masks can block anywhere between 50% and 70% of aerosols and larger droplets. And masks confer that kind of protection whether the person (or people) you come into contact with are visibly symptomatic or not.
So now more than ever, there’s no excuse not to mask up.
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.
This article originally appeared on HuffPost and has been updated.