The new shortened quarantine rules: what you need to understand to be safe.

The CDC has shortened guidelines for isolation after CVOID-19 infection, moving to five days of quarantine followed by five days of mask wearing. The agency indicated, “The change is motivated by science demonstrating that the majority of SARS-CoV-2 transmission occurs early in the course of illness, generally in the 1-2 days prior to onset of symptoms and the 2-3 days after.” But Director Walensky also commented “It really had a lot to do with what we thought people would be able to tolerate”.

Drs. Fauci and Walensky announce the new quarantine guidelines.

In general, I support the CDC’s reduction of quarantine from 10 to 5 days in unvaccinated individuals (and essentially ending it entirely in vaccine boosted, asymptomatic individuals). However, there are several issues people need to understand about this change that weren’t made clear by the CDC. In addition, there are a few actions people can take to assure that despite the shortened interval they are not putting themselves or others at risk.

First, the initiation and duration of infection with COVID-19 has evolved dramatically over the past year and a half. With each new variant, the time from exposure to infection has decreased by approximately a day. This means that while initially it was five days between exposure to the virus and a productive infection (when you could infect others), with Delta it only took four days, and now with Omicron it appears to take only three days. Thus, you need to isolate as soon as possible after exposure to keep from infecting other individuals.

Isolating sooner may be difficult, especially with Omicron, since many individuals are asymptomatic. We could have facilitated this process by making rapid testing widely available as it is in the United Kingdom and Europe, however this was not accomplished in the U.S. If you can obtain a test, use it, and if the result is positive, you are infected. If not available, you must assume you are infected and immediately self-isolate, with the good news that you only have to do it for five days.

A significant factor shortening quarantine is that people with prior immunity (be it from infection or from vaccination) are not infectious for as long as COVID-19 naive people. This means that it is safer to stop the quarantine after only five days. Also, despite what the CDC has previously suggested, I think most studies indicate vaccinated individuals do not shed as much virus. This means they are less likely to spread infection.

Despite this, there are two caveats on virus shedding and immunity. One is that unvaccinated individuals may be infectious for a long time, especially with higher replicating variants like Delta. Therefore, unvaccinated individuals should be more careful about ending their quarantine and should consider staying in quarantine for longer than five days.

Also, the amount of virus people produce when infected varies greatly between individuals even with the same vaccination status. This means that while most vaccinated people will most likely not be very infectious after five days, some could be very likely to infect others.

The best solution to the aforementioned concerns about ending the quarantine after five days is to have people test themselves with rapid antigen detection kits. This has been recommended by most public health experts including Dr. Jerome Adams the prior surgeon general.

Antigen tests for COVID-19 omicron. The test on the left is positive.

Antigen test kits have two major advantages. They are rapid so results are obtained in 10 minutes, and there’s no question about when to end the quarantine. More importantly, unlike PCR tests that detect minute amounts of virus or even dead virus, the antigen test does not detect small amounts of virus. Therefore, if an antigen test is positive, you’re likely to still be able to infect other people.

This test was not recommended by the CDC in no small part because of the government has failed to assure a supply of these tests. In another apparent effort to cover up this problem, an FDA press release yesterday suggesting rapid tests were “less sensitive” for omicron but provided no data. The way they said the test was conducted (heat treating the samples) certainly could have degraded the virus altered the results.

Regardless of all this noise, if you can obtain and use a rapid antigen test, and if it is negative, you can end your quarantine and can put everyone’s mind at ease!

Published by jbakerjrblog

Immunologist, former Army MD, former head of allergy and clinical immunology at University of Michigan, vaccine developer and opinionated guy.

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