1/In order to limit the importation of the variant coronavirus from the UK, CDC now requires travelers to be tested before boarding a flight. The strategy is insufficient because it's overly reliant on diagnostic tests that can't detect the virus in early stages of infection https://twitter.com/CDCgov/status/1343648170295885826

2/CDC requires a negative test up to 3 days prior to flight. One problem is you can test negative but catch the virus in intervening days. Another is that tests, even the gold standard PCR test, misses the virus in the early stages of infection & provides a false sense of safety.

3/This study, for instance, shows that on the day of the infection, the PCR test misses 100% of the cases. Each day after that the detection rate improves, but even by Day 5, when viral load tends to be high, these tests miss over a third of infections: https://bit.ly/2Hykuzk 

4/This was one of the reasons behind the super spreading event at the White House. People were tested, thought it was safe, and walked into disaster. These tests are designed to confirm infections, not to rule them out.

5/In addition to tests, we should require quarantines for travelers, and not just those from the UK. These variants are in other countries too. Some countries we know about, some we don't yet know about. And we need to get serious about eliminating Covid here at home #ZeroCovid