The latest studies show vaccines don’t really work against Omicron, only boosters. And vaccines were already fading fast.

(Originally published Dec. 9 in “What in the World“) The U.S. has managed to vaccinate 200 million residents, as Omicron sparks a late surge in inoculations among the hesitant. That’s still just 60% of the population, however, well short of the proportion needed to achieve herd… well, it’s just nowhere near enough.

Even countries with more than 80% vaccination rates are seeing a surge of infections this winter. Herd immunity now seems a myth when it comes to Covid. Countries just didn’t vaccinate enough people fast enough to create a herd and, besides, the vaccines are much less effective against Delta than the earlier strains they were designed for.

Just ask Portugal, where 89% of the population is fully vaccinated, but 25% of the population is now six months past their original vaccination date and so needs a booster. The U.S. getting to 60% vaccinated means little, therefore, when you realize that 45% of Americans had been vaccinated six months ago, and only 14% of the population has received a booster.

That means almost a third of the U.S. population has become, for all intents and purposes, unvaccinated. And so they have rejoined the ranks of the 40% who still haven’t been vaccinated at all when it comes to vulnerability to Delta. Or, put another way, the true U.S. vaccination rate is now really only about 30%. And that helps explain why U.S. infections are rebounding so sharply.

That’s even more worrisome given the latest announcement from vaccine makers Pfizer and BioNTech, who largely confirmed the findings of a South African study: saying that the first, two-doses of their vaccine Comirnaty was largely ineffective against the new Omicron infection, but would likely prevent severe illness. Only a third shot—a booster—appeared to offer the same kind of protection against Omicron that a two-dose vaccination now provides against Delta.

The companies didn’t say how soon after the first two doses the booster would prove effective, or how long afterwards. This makes their advice almost useless in determining your vulnerability to Omicron. The individuals in their study who had received boosters had received them a month before the test, when their immunity was presumably at its peak. The CDC doesn’t recommend getting a booster until six months after receiving the first two doses. The Pfizer/BioNTech study tested individuals who had received their first two doses only three weeks prior to the test, which is when immunity is also at its strongest and after which it starts to fade. So it’s unclear just how little protection against Omicron an initial vaccine provides after, say a month, or five, or how long the protection from a booster would last after that first month.

And bear in mind that the current vaccine offers pretty much the same promise against Delta: you may still get infected if exposed, but are unlikely to suffer severe illness if infected.

What we still don’t know is whether Omicron actually even causes severe illness and whether we need boosters to defend ourselves against it to remain healthy. Heck, we don’t even know for sure if Omicron is really more contagious than Delta. South African hospitals are now seeing a spike of infections among children who visit for other problems unrelated to Covid. So it appears infections are soaring even if illness isn’t. Or maybe more kids are just getting hurt and therefore more are getting tested for Covid. By the time we have the kind of data needed to know for sure, Pfizer et. al. will likely have developed a new vaccine tailored for Omicron. The question then will be: do we need to get one new-and-improved vaccine? Or will we need to roll up for two, for old Covid and new Covid?

That’s why the World Health Organization is urging nations to speed up vaccination campaigns and step up measures to restrict transmission. We need to make sure everyone is inoculated against both Delta and Omicron, i.e. vaccinated and boostered, to finally stanch the now-seasonal cycle of infection and prevent the emergence of yet another, potentially more dangerous, strain.

This goes doubly if you happen to be carrying some extra pounds. New research has found that Covid attacks fat cells, causing an inflammatory immune response that raises the likelihood of death. It also may explain the apparent correlation between Covid mortality rates and obesity rates. Covid seems more dangerous in patients with pre-existing conditions, many of which like diabetes are caused or exacerbated by obesity. Now it may turn out that those higher mortality rates are caused by the prevalence of obesity itself and not only by obesity-related health issues.