Breaking news analysis: How to make the new US test-to-travel from China policy achieve its goals.

A couple of tweaks could make a huge difference.

The US Centers for Disease Control and Prevention announced today that it will again require a negative Covid-19 test within 48 hours of travel from China. The policy goes into effect on January 5th, and will also apply to travelers coming from Seoul, Vancouver and Toronto, three other major hubs of travel from China.

The policy has two goals:

1. Slow down the entry of new Covid-19 cases into the US whose genetics are unclear.

2. Increase the overall tracking and detection of new variants.

The first goal is basically reasonable, given the lack of transparency on new Covid-19 cases in China. The virus is out of control there, and we have little reliable information on how bad things are, and what variants may be spreading. While test-to-travel policies can’t eliminate new cases (or new variants) coming from abroad at this stage of the pandemic, decreasing cases in general (even if only by 50% from a country with 1.4 billion people and apparently tens if not hundreds of millions of new cases) stands to benefit us, not to mention make travel safer.

How much of a dent the testing requirement will make in the mix of cases in the US is unclear. It’s not as if travelers from China comprise (or will likely soon comprise) a large fraction of our new Covid-19 cases. But every bit helps.

At the same time, among Covid-19 patients, PCR tests can remain positive for 2-3 weeks. To address that, the current US plan permits anyone 10 days out from a first positive test to enter from China, just as if they were negative. The problem is that many people (up to 20% by some estimates) are still contagious after 10 days, and transmission at this phase of illness has been documented. New variants could have longer contagious windows. That’s information we would want to have.

The second goal—identifying any potentially dangerous new variants—seems to be the more important one; there is concern among scientists that the sheer number of new cases in China is increasing the odds of a new and potentially dangerous variant emerging.

The problem is that the new travel policy is less likely to achieve this objective. Required testing prior to travel into the US will occur in China. The results of any genomic testing looking for new variants will be in the hands of Chinese officials. So even if scientists in China intensify their search for new variants as a result of our new testing requirements (and that’s a big if), that does not mean they’ll share the results with anyone.

It seems to me that the US government’s new policy has some laudable goals, and has some chance to achieve them. But I think we could make some tweaks to improve the policy in order to reach the stated objectives. So…

Here’s my advice to the CDC and the White House for how to improve its new travel from China policy:

1. Require a negative rapid antigen test for anyone traveling from China (or anywhere, for that matter) who has had Covid-19 in the last 2-3 weeks.

2. Rather than rely on China to increase its surveillance for any possible new variants, we should take this project into our own hands at major hubs of travel. Companies like Phylagen have had success swabbing surfaces looking for Covid. While SARS-CoV-2 does not predominantly spread via surfaces (as we believed in early 2020), its viral particles do in fact accumulate on them, and can be stable for quite some time. It seems to me that we could be swabbing surfaces at airports, on planes, and other highly populated settings in search not of individual new cases, but, rather, in search of new variants that might cause trouble.

The irony here is that I learned about the second approach (swabbing surfaces looking for under-the-radar Covid) at the White House! When I attended the White House’s Indoor Air Quality Summit in October, I learned about how a company called Phylagen was hired by a New York real estate company to swab surfaces in its offices, finding new cases well before anyone knew about them. There’s no reason why using this approach to pick up new variants can’t succeed—especially since we can do it ourselves, instead of relying on the cooperation of any other power.

Covid-19 risks at airports are probably misunderstood in both directions. They don’t seem to have the superspreader conditions that many feared, thanks to good air and, earlier in the pandemic anyway, mitigation measures like masking and testing. But that does not mean they are Covid-19 free. Indeed, airports and airplanes can play host to some degree of spread. In this way, they might be an untapped resource. Today’s new travel policy may not tap into that potential yet, but perhaps it can be harnessed to do so.