You’ve got the jab, but how much can you now socialise?

A year and a half into the pandemic, people are more confused than ever about the risks they face, and that goes for experts and lay people alike. Cases and hospitalisation are going up in almost every US state, but the messages we’re getting are mixed about the risks to the fully vaccinated. 

The New York Times recently reported that in a limited number of states that do such reporting, 12%-24% of people hospitalised for Covid-19 are fully vaccinated. We’ve heard that the vaccine is wearing off fast in Israel, where Covid-19 is in a raging surge, and that in the UK, the majority of recent deaths have been among the vaccinated. And yet the Centers for Disease Control (CDC) has used data from Los Angeles County to produce the more reassuring statistic that unvaccinated people are 29 times more likely to be hospitalised than the vaccinated.

Part of the problem is that numbers can be spun different ways, depending on whether the object is to persuade people to get the vaccine or to persuade the vaccinated to wear masks in public. The other part of the problem is that the data is much more limited than they should be.

That leaves the public with many unanswered questions. Should we wait till we get a third shot before we go back to having social lives? How much will a booster help? Are vaccines wearing off or is it just that they’re not quite as good at protecting people from the Delta variant?

In May, the CDC stopped tracking infections among vaccinated people unless they were hospitalised. It was reasonable given that what matters most is, of course, severe disease and death, and resources are limited.

But the lapse in data-gathering was worse than that, said Eric Topol, a physician who is director of the Scripps Research Translational Institute in La Jolla, California, and the author of a recent piece in The Guardian titled “America is flying blind when it comes to the Delta variant”. It turns out that hospitalised people haven’t been systematically tracked either, beyond limited local data used for studies.

“We now have over 102,000 hospitalised Americans, and we have no idea what proportion are vaccinated or not vaccinated,” Topol told me.

For everyone admitted to a hospital, even in the most overwhelmed states, it should be a simple matter to record ages, whether the patients were vaccinated, which vaccine they received and when. It’s the kind of data Americans might assume was used to back the recent decision to recommend boosters to everyone eight months after our initial shots. When I looked into the booster rationale for a previous column, I found there was no expert consensus on whether the efficacy of vaccines was waning over time or whether we’re seeing the effects of the more contagious Delta variant coupled with people reverting to more typical social lives.

Right now, we’re relying on data out of Israel for recommending boosters, but it would be much better for the US to have its own data than to try to extrapolate from the experience of other countries. If the unvaccinated are really 29 times more likely to be hospitalised, why are boosters so urgent?

It’s hard to judge whether we save more lives by giving all Americans booster shots, or by shipping our excess vaccine doses overseas where they can help protect us from another, more dangerous variant emerging in a country with a low vaccination rate, the way Delta emerged from India’s monstrous spring surge.

As an opinion piece in The New York Times titled “Show Me the Data!” detailed, experts are grappling for answers on Twitter, which doesn’t inspire a lot of confidence. Data is particularly scarce in the contentious area of risk to children, who can’t yet be vaccinated. The US has also failed to do the contact tracing studies that could help identify the activities or venues that pose the greatest risk.

The trouble isn’t entirely the CDC’s fault. Last week Politico revealed that many state and county health departments were failing to collect data on vaccination status of hospitalised patients, so the CDC wasn’t able to obtain the needed data from many areas. These local health departments complained they hadn’t been given the resources to do this reporting. It seemed to be a breakdown in a system that should have required some organisation on the part of local health departments and the federal government.

Data matters not just to government decisionmakers, but, increasingly, to all of us, as we are now expected to use our own understanding of risk to navigate our lives. We’re now allowed to travel, gather and go to restaurants based on our own judgment, while getting mixed messages about whether any of this is reasonable to do if you’re vaccinated.

Most experts seem to agree that big gatherings are a major factor fuelling surges, especially ones that bring people together repeatedly, such as weddings or the July Fourth celebration in Provincetown, Massachusetts. But, as Harvard epidemiologist William Hanage and others have pointed out, the risk depends a lot on how much the virus is circulating in a given community, and that’s not always easy to ascertain.

When the media does supply numbers, they are often presented in an ambiguous way, perhaps meant to capture attention more than to inform. News outlets widely reported the CDC’s assertion that 99.99% of vaccinated people didn’t get a breakthrough infection bad enough to go to the hospital — so only .01% needed hospitalisation. But Scripps’s Topol points to contradictory numbers showing that 1% of infected people in the Provincetown outbreak were hospitalised.

That’s a difference of a factor of 100 — which is pretty big — but there’s some confusion over the denominator. The Provincetown number looks to be based on the percent of hospitalised patients out of all vaccinated people who tested positive, but the CDC’s 99.99% number might be measuring something different — the number of hospitalised vaccinated Covid patients compared with all vaccinated people.

That would be a strange statistic to gather. Even if the unvaccinated are 29 times more likely to require hospitalisation, that means their odds still look pretty good, with 99.71% not getting hospitalised. 

Too often numbers are thrown around to try to persuade people to get vaccinated — but there aren’t enough numbers to really help people navigate once they are vaccinated. This is no longer just about getting our shots and wearing a mask to the supermarket. The CDC recently advised older people not to go on cruises, even if vaccinated, but what about other kinds of trips, or a daughter’s wedding, or just getting together with friends? Should younger people visit our older friends or relatives who are lonely and eager for company?

The most vulnerable among us are sometimes more likely to choose to take risks because they don’t have that much time left. At the very least the government and media owe them the information they need to choose wisely.

Bloomberg Opinion. More stories like this are available on bloomberg.com/opinion