Opinion

May 22, 2023

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Two months ago, I wrote about how to make sense of a study that seemed to imply that N95 masks were no better than surgical masks in protecting against the coronavirus. In short: That was the wrong interpretation. A high-quality respirator mask provides better protection against respiratory viruses than lower-quality masks.

Now, there is more mask confusion thanks to the release of a new review of masks published by Cochrane Library. “We are uncertain whether wearing masks or N95/P2 respirators helps to slow the spread of respiratory viruses based on the studies we assessed,” the authors concluded.

Some have taken this to mean that masks don’t work to protect against the coronavirus. I received messages from concerned readers who are now doubting whether they should keep masking.

John from Wisconsin, for example, writes: “I am an immunocompromised 78-year-old and wonder if I should continue wearing a mask at places like stores, the YMCA and crowded restaurants. I wear masks in these situations but have read that masks are not efficacious.”

John should keep wearing a mask in these settings if his goal is to reduce his chance of contracting the coronavirus. Unmasking because he thinks masks don’t work to protect him is a dangerous misinterpretation of the Cochrane findings.

First, I want to acknowledge that Cochrane is a highly reputable source. Its systematic reviews are considered the gold standard of medical analysis. But, as with all other research, any interpretation of its findings should take into account the methodology, the question being asked and the limitations.

In this case, reviewers examined 78 randomized controlled trials that looked at the impact of physical mitigation measures, including masking. These studies took place around the world. Many were conducted before covid and assessed the impact of masking on preventing influenza and other viral illnesses.

The main question the analysis reviewed was whether physical interventions can “interrupt or reduce the spread of acute respiratory viruses.” This is a population-level question — that is, it primarily asks whether masking reduces the spread of viruses in the community rather than whether it protects individuals from contracting the disease.

The authors acknowledge numerous limitations, the most significant of which is that in many of the studies, compliance with masking was low. And masks work only if they are worn consistently and properly.

Based on the Cochrane review, I think it’s fair to conclude that evidence doesn’t support masking to reduce community transmission if adherence is variable. Controlling highly contagious respiratory viruses such as omicron subvariants is extremely challenging, and intermittent masking is probably ineffective as a population-level intervention.

I also agree with the authors’ conclusion that we need more well-designed randomized controlled trials around masking and, crucially, an accounting of the harms of masking. In certain populations, such as young children, the harms might outweigh the potential benefits, especially if there is limited, if any, benefit of masking to protect others.

But it would be wrong to conclude from the review that everyone should stop masking because masks no longer protect the mask-wearer. Even if mask recommendations might not have a population effect, high-quality masks still work on an individual level if that person consistently wears them.

The science hasn’t changed: Well-fitting N95, KN95 or KF94 masks protect their wearers against covid and other respiratory diseases. John and others who are elderly, immunocompromised or otherwise want to avoid covid should continue wearing them in indoor crowded spaces.

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“Although I haven’t had covid and am up to date on all vaccines, my ace in the hole has been my knowledge that, if infected, I can get Paxlovid (I’m in my 70s). My understanding is that Paxlovid is only authorized for use while the national emergency is in effect. If President Biden lifts the emergency on May 11, does that mean Paxlovid is no longer authorized for use? This could be a major problem. Can we lift the emergency and have our Paxlovid as well?” — Katie from Utah

The Biden administration has clarified that the end of the national emergency for covid will not affect the emergency use authorization (EUA) granted for vaccines and treatments. The Department of Health and Human Services reports on its website, “Existing EUAs for covid-19 products will remain in effect under Section 564 of the Federal Food, Drug, and Cosmetic Act, and the [Food and Drug Administration] may continue to issue new EUAs going forward when criteria for issuance are met.” Paxlovid, along with other treatments, vaccines and tests,, will remain available through the existing EUA.

“Terminology about vaccinations/boosters is tricky, confusing and critical. For example, in your column last week, you say, ‘officials have not yet authorized a second bivalent booster.’ Does this mean a shot beyond the original bivalent vaccination we got in September? Or a shot after a first booster of the original vaccination taken sometime after the September injection? We are both 76 and highly immunocompromised.” — Thomas from Pennsylvania

To clarify, the FDA has authorized two types of vaccine formulations for the coronavirus. One is the original, or monovalent, vaccine, which was developed against the ancestral coronavirus strain and authorized in December 2020. People who were vaccinated when these shots first became available received this formulation, and immunocompromised individuals could have had up to three boosters — for a total of five shots — of this vaccine.

In September 2022, an updated bivalent vaccine became available. This one targets both the original strain as well as the BA.4/BA.5 omicron subvariants. Early studies show that this bivalent vaccine is at least as effective as the original monovalent vaccine against the now-dominant omicron variant.

At the moment, federal health officials have authorized only one dose of the bivalent vaccine. Even older individuals with immunocompromise can technically receive just the one updated booster. Many readers have been asking whether they can receive another booster. The FDA and Centers for Disease Control and Prevention have not yet given formal guidance on this. When they do, the additional booster would not be with the original vaccine, but with the bivalent formulation. I hope that this advice will be forthcoming soon, as there are many people in your position wondering when they can receive another dose.

“It’s my understanding that people who use at-home testing for covid are not required to report their positive results. Yet everyone I know who contracted covid has used at-home testing unless they’re symptomatic and testing negative. Then, they get a PCR test. Doesn’t this severely undercount the number of covid cases reported by the various agencies?” — Britta from California

Yes, you’re right. In some ways, this development is a good thing. Remember the early days when testing was so limited that only hospitalized patients could get tested? Then, during the omicron surge, pharmacies were sold out of at-home tests, and even symptomatic people had to wait in long lines to get PCR testing.

Now, we have abundant testing options. False positive at-home tests are rare, and there is no need to confirm a positive result with a PCR test.

The downside is what you pinpointed: Official coronavirus case counts are no longer accurate. Actual infection numbers are much higher due to at-home tests that are never reported to health agencies.

This means other metrics will also be inaccurate. When most tests were being tracked by health departments, test positivity was a helpful proxy for understanding trends in infection rates. Now, it’s hard to know what test positivity trends indicate. Plus, the severity of disease is almost certainly being overestimated: If there are far more cases than are being reported, then the actual proportion of cases that progress to severe disease is probably much lower than the official numbers indicate. (Hospitalization numbers are inflated as well.)

The Post has also compiled Q&As from my previous newsletters. You can read them here.

In this meta-analysis published in Lancet Infectious Diseases, researchers examined articles that looked at the protective effect of prior coronavirus infection alone compared with hybrid immunity (the combination of both vaccination and recovery). They found that people with hybrid immunity had far superior protection. At 12 months, effectiveness of previous infection against hospital admission or severe disease was nearly 75 percent, versus more than 97 percent for hybrid immunity. In the same time frame, protection against reinfection waned to about 25 percent for those with previous infection versus around 42 percent for those with hybrid immunity. As the authors wrote, individuals with hybrid immunity “might be able to extend the period before booster vaccinations are needed compared to individuals who have never been infected.”

Pediatrician and vaccinologist Paul Offit wrote a thoughtful — and controversial — piece in the New England Journal of Medicine. As an external adviser to the FDA, Offit publicly expressed opposition to annual coronavirus boosters for generally healthy individuals. As he argues, “Booster dosing is probably best reserved for the people most likely to need protection against severe disease. … I believe we should stop trying to prevent all symptomatic infections in healthy, young people by boosting them with vaccines containing mRNA from strains that might disappear a few months later.”

A number of readers have asked whether the bivalent booster is effective against XBB.1.5, the colloquially named “kraken” variant that now comprises nearly 75 percent of new coronavirus infections in the United States. According to a new CDC study, the answer is yes. Across age groups, vaccine effectiveness was generally similar among those with infections from earlier BA.5 variants compared with XBB and XBB.1.5. Specifically, early vaccine effectiveness against symptomatic infection due to XBB/XBB.1.5 was 49 percent among people aged 18 to 49; 40 percent among those 50 to 64; and 43 percent among those 65 and older.