Skip to content

Tag: BA.2

Published on Leave a comment on Roller Coaster Week

I guess we all should be accustomed to the ups and downs of the pandemic. We continue to see good news with waning of the omicron surge around the world, but parents of children under 5 had a bit of a jolt on Friday with the news that the Pfizer vaccine will not be discussed by the FDA next week as originally planned. We now await ongoing data from the trial which has begun a booster dosing phase. Regular readers of Pediatric Infection Connection will know that I oversee this trial at Children's National Hospital, but I have no knowledge of the data submitted by Pfizer to the FDA so can't provide any independent opinion.

Booster News?

Speaking of boosters, CDC released some important new information about boosters, some of which pertains to children. First, an early release in MMWR highlighted waning of effectiveness of 2- and 3-dose mRNA vaccines. This is sort of a glass half empty or full view, I was actually more encouraged by the continuing effectiveness, particularly for boosted individuals, against severe disease and hospitalization. Just looking specifically at the data from the omicron-dominant time period, vaccine efficacy (VE) in preventing emergency or urgent care visits was 87% 2 months following a third or booster dose though dropped to 66% beyond 5 months (note few data available for this latter estimate). VE in preventing hospitalization was 91% and 78% for those 2 intervals post third dose. This is by no means the final word, lots of limitations in this study and also it looked only at individuals 18 years of age and older and did include a significant number of people with immunocompromise and other risk factors for severe COVID-19 disease. No information about how these risk factors specifically affected VE.

Also, as promised the CDC issued an update to guidance for vaccination of those with moderate or severe immunocompromise to include a fourth dose in some circumstances. This update applies to people down to 12 years of age and provides a good road map for vaccination of those individuals.

Variant Viewing

I'd definitely be happier stargazing or watching butterflies and bees in season, but lately I've been keeping an eye on the BA.2 subvariant of omicron. It has started to appear in our CDC data (after clicking on this link, choose Variants and Genomic Surveillance, then Variant Proportions from the left-side menu). BA.2 now comprises 3.6% of isolates as of Feb 5 compared to 96.4% omicron BA.1) and similarly has increased slightly in the UK. As I indicated last week, it is more transmissible than the original omicron variant, but it isn't clear whether prior infection with omicron BA.1 confers some immunity against BA.2. That is probably the key factor in determining if we will see another surge due to BA.2.

I also note some encouraging news in the UK that the reproductive number is now estimated at 0.8 to 1.0, a milestone that signals flattening or decrease in the pandemic. Of course it could be just another ride on the roller coaster but I choose to take this as a further good sign.

Published on Leave a comment on 6 More Weeks of Winter

Apparently Punxsutawney Phil saw his shadow this week, but maybe you didn't know about this important groundhog connection to the world of infectious diseases. Woodchucks (aka groundhogs) are affected by WHV (woodchuck hepatitis virus) and have been used in hepatitis B research. Unfortunately, Phil's forecasting accuracy rate for winter weather duration of 40% might be better than most models of COVID-19 future waves.

Important Conversations at ACIP

I didn't see much about this in the lay press, but the Advisory Committee on Immunization Practices met on February 4, primarily to discuss the recent FDA approval for the Moderna mRNA vaccine that will now be marketed as Spikevax. That all went fine, but I was more interested in the afternoon discussions.

  • Tracking of vaccine-associated myocarditis continues with further data from both the US and international sites. Although there are no large randomized controlled trials directly comparing the 2 mRNA vaccines, it seems likely that this risk is slightly higher with the Moderna vaccine than with Pfizer's. However, both risk rates are considerably lower in comparison to the risk of myocarditis from natural infection. I think the best way to use this information might be to advise a male adolescent or young adult, the highest myocarditis risk group, to choose the Pfizer vaccine when starting a primary series or considering a booster. The vaccine-associated myocarditis still seems to be very mild with no long-lasting sequelae, but well-designed long term follow-up studies are ongoing.
  • The other discussion I found very interesting was regarding the interval between first and second doses for a primary mRNA vaccine series. Canada and other countries now have a fair amount of data on this; in the US this has not been well-studied, and in the initial vaccine research trials virtually all of the participants had second doses at around 3 (for Pfizer) or 4 (for Moderna) weeks after the first. Based on the meeting presentations, consensus of ACIP members seemed to lean heavily towards recommending an 8-week interval between the first 2 mRNA vaccine doses, especially in times of low community COVID-19 activity where risk of infection during that more prolonged interval between doses will be less.
  • Also, stay tuned in the next few days (I think) for more specific and very helpful guidance on immunization of individuals with moderate or severe immunocompromise. This will be very helpful to those patients as well as to providers who advise transplant and other patients on this topic.

Alas, Poor Yorick

I must admit I don't know much about Denmark: it is the origin of the name for epidemic pleurodynia, Bornholm disease, and it is the setting for what is perhaps Shakespeare's best play. Now, Denmark is in the COVID-19 spotlight for 2 reasons.

First, a recent preprint shows us that the new omicron "subvariant," BA.2, has become very prominent in Denmark. The study looked at primary cases of COVID-19 from December 20, 2021, to January 11, 2022, to identify secondary attack rates in those households. Tracking of secondary attack rates ended January 18, and testing of household members was relatively high. From the 8541 primary cases in households, 5702 out of a potential 17,945 exposed household members were infected. When broken down further, the secondary attack rates for BA.1 (the original omicron) and BA.2 were 29% and 39%, respectively. This provides further evidence that BA.2 may be slightly more infectious than BA.1. Vaccination of exposed individuals didn't seem to affect secondary infection rates, but note that this included asymptomatic infections; there was no evidence of increased disease severity of BA.2.

I'm especially interested to watch how this all unfolds in Denmark, both because they are experiencing relatively high percentages of BA.2 and because they have just instituted one of most relaxed mitigation strategies anywhere.

It's hard to guess whether BA.2 has the potential to cause additional new disease surges after BA.1 across the world. Try asking Punxsutawney Phil.

Unless otherwise indicated, the content and opinions expressed on this web site are those of the author(s). They are not endorsed by and do not necessarily reflect the views of the George Washington University.
Viewing Message: 1 of 1.
 Notice

This site uses cookies to offer you a better browsing experience. Visit GW’s Website Privacy Notice to learn more about how GW uses cookies.