CDC vs. WHO on masking

The WHO is urging vaccinated people to wear masks, while the CDC is saying that it’s not necessary. This has, rightfully so, led to confusion and misinformation. Why would their guidance differ?

Very different landscapes

The WHO, an arm within the United Nations, serves more than 150 countries. And each of these countries have different transmission rates, vaccination rates, disparities, genetics, behaviors, politics. etc. The WHO is looking at a world that is only 19.6% fully vaccinated and, among those 150 countries, vaccination rates vastly differ: 40 countries have <2% vaccination coverage; 13 countries have >50% coverage; and, 97 countries land somewhere in between. The WHO has to approach public health as a population-level threat.

On the other hand, the CDC is looking at a “world” that is 46.4% fully vaccinated. And although states within the U.S. also greatly range (33% in Mississippi- 71% in Vermont), the CDC has set the tone that the pandemic is an individual-level threat. (I and others have voiced concern over this dangerous approach).

Population- vs. individual-level health are very different strategies. So, the recommendations and the implications of those recommendations will differ.

On a population-level, why do fully vaccinated need masks?

I assume the conversation at WHO (and Los Angeles Health Department, and Israel, and others reenforcing masks) is driven by the following three factors:

1. Vaccinated people still have the small possibility of playing a role in the transmission chain (although WHO and CDC still disagree on how small “small” is). Breakthrough cases will also happen. If SARS-CoV-2 is spread into a highly unvaccinated community (which is now more likely given the super variant Delta), the damage could be great. Widespread disease could also lead to another variant that’s able to escape vaccines altogether. We need to stop transmission at every corner.

2. We are waiting to see how well vaccines work against Delta. We know the two-dose mRNA vaccine works well against Delta. Same with AstraZeneca. We don’t know how well Johnson & Johnson works yet (although I’m optimistic). There are a total of 8 vaccines authorized and 8 vaccines approved across the globe, and we are still learning a lot about their effectiveness against variants of concern.

3. There is value in normalizing masks. Think of it as a trickle down effect. If masks are recommended, then countries/states/territories mandate them, then businesses endorse and enforce masks, then individuals (vaccinated and, more importantly, unvaccinated) will wear masks. And if adults wear masks, the kids will too. Unfortunately, we saw in the U.S. how quickly this crumbles. An honor system just does not work.

So, should a fully vaccinated person wear a mask?

On an individual-level, you will be protected from severe disease. At least for now. And, using this approach, only you can continually evaluate your risk tolerance level.

But individualism does not end a pandemic. Especially given how quickly Delta is spreading. I strongly suggest the vaccinated to continue to mask indoors. Especially if…

• …you’re in a low vaccination area (less than 50%)

• …you’re in a high transmission area (more than 10 cases per 100,000)

• …you’re immunocompromised

• …you have kids or high risk adults at home

• …you’re sick

We cannot trip with the finish line in sight.

Love, YLE