This week brings new guidelines for quarantine, new research into duration of virus shedding, and ongoing developments in vaccine development and approval. If you wish to receive it by email, you may register for free, here.
1. CDC Adds Quarantine Options
This past week, multiple media reports stated the CDC was changing its recommendation on quarantine. Yesterday, the CDC published its final recommendations and a few important points became clear.
- The change applies to people exposed to COVID-19 only.
- The CDC still recommends a 14 day quarantine period.
- Recognizing the difficulty in compliance with a 14 day quarantine, they provided two alternative options that have the risk of missing 1-12% of cases.
Option 1 is a 10 day quarantine. This does not require any testing at the end of 10 days and is similar in duration to the 10 day period currently suggested for isolation of someone who tests positive. The CDC estimates this strategy will miss about 1% of cases, with a maximum of 10%.
Option 2 is a 7 day quarantine with a test at the end. The test can be conducted up to 48 hours before the end of the quarantine period in order to facilitate processing results. This strategy is similar to previous published strategies by Yale and other institutions. The CDC estimates this option may miss 5% of cases, with a maximum of 12%,
Why would we adopt a strategy that would miss cases? The important caveat for these two optional strategies is the requirement for continued mask use, distancing AND the continued monitoring of symptoms until a full 14 days has passed. So, though someone may be cleared to return to work or school, they are expected to continue monitoring for symptoms and use protective measures. In schools and businesses that are already using masks and symptom monitoring, the risk of exposure is low and likely to be on the lower end of the spectrum.
So how is an institution expected to make this decision? The answer here is a combination of risk tolerance and compliance with quarantine.
- If the population you serve is having difficulty complying with the 14 day rule, or worse, not reporting symptoms because of the length of quarantine, then a shorter duration may improve compliance. In this case, you likely already have an increased risk because people are not reporting symptoms.
- If the population you serve is compliant, reports symptoms regularly, and is very averse to missing a case and having a classroom or business close temporarily due to a covid exposure, then it is better to keep the recommended 14 day period.
What do we recommend? Taking into account the increased number of cases, the difficulty obtaining testing in some areas, and the hesitance to report symptoms due to a lengthy quarantine, we like the 10 day option. Isolation for a positive test result is already 10 days. This is often confused with the 14 day requirement for exposure. Reducing the exposure period to 10 days makes both rime frames the same. This is not only easier to administer, but reduces confusion and does not require an additional risk. In most areas already requiring masks and distancing, the risk is reported at 1%. That is acceptably low. So, we like option 1.
2. Duration of COVID-19 Infectious Period
A new review in the journal Lancet confirms that patients infected with SARS-CoV2 (COVID-19) may have persistently positive test results after infection. They found that these same patients do not shed “live virus” after 9 days. This means that people may have positive test results detecting pieces of the virus for long periods of time after infection. However, these fragments are not “live virus” and not capable of causing infection in others. The study also found that older age led to longer periods of viral shedding, but none longer than 9 days. This is welcome news. However, a second study in the New England Journal of Medicine (NEJM) found that patients who are immunosuppressed may shed live virus for up to 2 months. Specifically, they studied 11 patients undergoing cancer therapy who became infected with COVID-19 and found that they shed live virus for up to 2 months. Though it is a small study, it adds important information to our knowledge on who may still be contagious past 9 days. People who are immunosuppressed include those receiving chemotherapy, on long term steroid therapy, and with a history of immune deficiency.
3. Moderna To Begin Pediatric Testing
We discussed in previous newsletters the importance of vaccine testing in children. Though two COVID-19 vaccines have applied to the FDA for approval in adults, testing in children is still necessary before they can be approved for use in the pediatric population. Moderna announced its vaccine trial for children and will hopefully begin recruiting soon. It is important to remember that children and pregnant women are listed as special populations for medications and vaccines, requiring specific study in those populations before being approved.
4. U.K. Approves Pfizer Vaccine
The United Kingdom has approved the Pfizer COVID-19 vaccine for use in adults. This has led many to question the U.S. FDA’s process for vaccine approval. However, there are significant differences in the approach to data analysis between the two organizations responsible for medication and vaccine approval. In the U.K., reviewers may rely on the data summaries and interpretation provided by the manufacturer but do have the option to perform their own independent review. In the U.S., the FDA takes a much more conservative approach, examining all the original data and producing its own interpretation of the findings. Though this process is certainly more lengthy, it allows the FDA to be more secure in its findings when they are published. As we await the FDA’s response to Pfizer and Moderna on their COVID-19 vaccine applications, it is important for us to allow the full review to be completed before we can confidently say the vaccines are effective and safe.
5. Who Will Receive The Vaccine First
As we get closer to the release of our first COVID-19 vaccine, many have been asking how long it will be before they can be vaccinated. The CDC has been discussing vaccine distribution for some time. Their recommendations are provided to individual states who then make the final decisions regarding distribution. However, it is anticipated that healthcare workers, people over age 65, people with high risk medical conditions, and essential workers will be the first to receive the vaccine. The federal government added teachers to the list of essential workers in August of this year. However, as the vaccine is distributed to individual states, it will be up to them to build their priority list and decide whom to include as essential worker.