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One simple way to understand how effective the Covid-19 vaccines are

All of the Covid-19 vaccines are more effective than your annual flu shot.

A person receives and injection in their arm from a health care worker.
The Johnson & Johnson Covid-19 vaccine, while less effective at preventing mild illness than Pfizer’s or Moderna’s, is still more effective than the average flu shot.
Joseph Prezioso/AFP via Getty Images
Dylan Scott covers health care for Vox. He has reported on health policy for more than 10 years, writing for Governing magazine, Talking Points Memo and STAT before joining Vox in 2017.

All of the approved Covid-19 vaccines — all of them — are more effective at preventing Covid-19 than the average seasonal flu shot is at preventing the flu. But you wouldn’t know it from how they’ve been talked about in some reports about the vaccines.

As my colleague Kelsey Piper wrote recently, the most important statistic about the vaccines approved for emergency use in the US — Pfizer/BioNTech, Moderna, and Johnson & Johnson — is zero: zero deaths or hospitalizations among the patients who were given the vaccines in their clinical trials. (In Israel, just 16 out of 700,000 people who were fully vaccinated were hospitalized with Covid-19, according to government data released in late January, or 0.002 percent. Nobody died.)

But that good news has been dampened somewhat because the media has focused on another number: efficacy, or how effective the vaccines are in preventing any illness at all, however mild it is. Viewed through that prism, the Johnson & Johnson vaccine (with a 66 percent efficacy rate) looks substantially worse than Pfizer/BioNTech’s or Moderna’s (both 95 percent efficacious).

But I’ll let you in on a secret: Even the 66 percent efficacy rate is an impressive result. You need only look at seasonal flu vaccines for proof.

The effectiveness of a flu shot varies from year to year because every year different strains of influenza are dominant. Scientists essentially have to play a guessing game, hoping they come up with the right concoction that provides as much protection as possible against the most widespread flu viruses that year, which they can’t predict in advance.

As a result, the CDC itself explains, “flu vaccination reduces the risk of flu illness by between 40% and 60% among the overall population during seasons when most circulating flu viruses are well-matched to the flu vaccine.”

Read that again. Even when scientists do a good job of matching the flu vaccine to the dominant flu strains, the flu shot that public health experts and media outlets spend weeks begging people to get every year is less effective on average than the Johnson & Johnson Covid-19 vaccine.

But the flu shot is still worth getting because even if a person gets sick after being vaccinated, their illness is probably going to be less severe than it otherwise would have been. Overall, the CDC estimates that the flu vaccine prevents 7.5 million illnesses, 105,000 hospitalizations, and about 6,000 deaths annually.

The same principle applies to the Covid-19 vaccines, which is why vaccine evangelists keep emphasizing zero deaths and zero hospitalizations. The fifth line in this chart is the real victory. People who get any of the available vaccines (AstraZeneca, on the list below, is still not approved in the US) are most likely going to survive the pandemic.

Zac Freeland/Vox

But the fourth line, on efficacy, is no slouch. Johnson & Johnson has produced a single-dose vaccine more effective than the seasonal flu shot that can be more easily stored than the other Covid-19 vaccines. It has a serious logistical advantage to vaccinating more people more quickly: The other approved vaccines have a two-dose schedule; J&J is approved for one dose. No one should feel they’re getting a raw deal if they end up with the J&J vaccine when they go to get their shot. (You probably won’t have a choice anyway; supply is too scarce.)

The future is looking bright. The number of people who say they’ll “wait and see” about getting a Covid-19 vaccine is shrinking and the number who say they will get their shot as soon as possible is growing, as the Kaiser Family Foundation’s Drew Altman wrote Monday. The US averaged 1.8 million vaccinations per day over the last week, up from its 1.3 million-shot pace a week ago.

We should remain vigilant. The US is still averaging 2,000 deaths reported every day and there are worrying signs that the recent decline in cases might be slowing, as public health experts warned me last week.

But the end may be in sight. And we have the vaccines — including, yes, that 66 percent efficacious Johnson & Johnson shot — to thank.

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