February 2022 – Pediatric Infection Connection

Yet Another Game Changer

Bud WiedermannFebruary 27, 2022Leave a comment

The CDC appears to have answered my question in last week's post, at least partially. While we are by no means in the clear, the new transmission prevention guidelines signal a more logical approach to NPIs (non-pharmaceutical interventions) that fits the current stage of the pandemic. On the other hand, we did see some controversy about whether the CDC is purposely withholding data from the public.

Is the New Guidance Too Confusing?

The guidance for specific areas depends on both disease activity and healthcare capacity for that region which makes a lot of sense because we know we won't reach herd immunity. Prevention of severe disease, death, and healthcare rationing are primary goals. We've seen healthcare taxed beyond capacity trying to care for both COVID-19 patients as well as all the other population health needs. CDC has set up a site that gives a specific answer for a community's level of risk (high, medium, or low) and corresponding advice. Just look at the color of your area of interest in their map and you will have the quick answer.

Getting to the underlying data for the categorization is a little harder but not terribly imposing. For example, if you wanted to know what's going on in Montgomery County, MD, you'd see that as of February 27, 2022, community transmission is "substantial" with the case rate at 66/100,000 and percent of positive tests at 1.83%. 4.43% of inpatient beds and 8.42% of staffed ICU beds are occupied by COVID-19 positive patients. What this all means, going back to the main site link, is that Montgomery County is in the Low community risk level.

I am most interested to see what happens in those jurisdictions where states have made pre-emptive rulings about NPIs that may contradict CDC's guidance. How many of them will toe the new line? Also, will citizens comply when their community experiences an increase in risk and should increase precautions?

Transparency is Essential

I don't have a problem with CDC or other agencies not releasing data that could be inaccurate, but I do have a problem with withholding information because someone might misinterpret the data. Just as with any scientific study, the investigators are obligated to discuss what the results mean and the limitations of the study.

Let's look at the example of wastewater testing and compare the US to the UK. Wastewater testing can be extremely valuable for tracking disease hotspots and also for tracking variants. CDC reports 15-day data on their website. You can see trends and activity in different parts of the country, though I couldn't find any information about variant tracking.

The UK, on the other hand, offers much more extensive information about wastewater tracking in monthly reports, including variant percentages across the country. The country coverage is much more extensive than in the US, though I didn't see any data from Wales.

Here is a screenshot of sites covered by wastewater tracking in the US. Large swaths of the country are not represented:

Dots represent data collection sites, with colors showing percent change. Red is bad, dark blue good, other shades in between, and gray with no recent data.

In general I wouldn't worry as much about misinterpretation of CDC data as I would about deliberate misuse of data. An example of the latter has been an ongoing problem with use of the Vaccine Adverse Events Reporting System (VAERS) data during the pandemic. Virtually every pediatric healthcare provider knew well before the pandemic that VAERS could not provide information about causation - anyone can report any type of event as being associated with a vaccine, and the reports are publicly available. That didn't stop many bad actors from using the data to falsely support claims of harm from COVID-19 vaccines.

In the Clear?

Bud WiedermannFebruary 20, 2022Leave a comment

I must admit a bit of surprise that so many "blue" states are relaxing NPIs (Non-Pharmaceutical Interventions) for the pandemic at a time when new case rates, while falling, are still quite high. Is this all too soon? Too late?

What Do the Models Predict?

Most of us don't have the mathematical background to critique the various pandemic models, but let's look a little closer at one of them. The Institute for Health Metrics and Evaluation (IHME) is an independent population health research organization based at the University of Washington. IHME was founded in 2007 and is one of my favorite sources for data and forecasting during the pandemic.

Let's look at their most recent data compiled February 17. This is a link I'd really encourage you to explore because as you will see the graphs are interactive. Although I've set the link to open for the view of the United States, you can search anywhere.

It's important to look at several different outcomes, especially in the omicron era, to get an accurate picture. We have lots of variability in healthcare seeking and testing behavior, plus as my wife reminded me most of those rapid home test results don't get reported to any public health authority. However, hospitalization rates are a reasonable assessment of what's going on plus focus on an outcome that we care about most. Here's a screen shot of IHME's current projection for hospital bed use in the US.

This is certainly encouraging, though projections will depend on what future variants have in store for us.

Variant Alphabet Soup

Writing in the BMJ, journalist Elisabeth Mahase reminds us that the World Health Organization first designated omicron a variant of concern on November 26, 2021. A lot has happened in the last 3 months. In Pango-speak (Phylogenetic Assignment of Named Global Outbreak lineages, a software tool) it is designated B.1.1.529.1, now BA.1 for short. It accounts for >90% of cases globally currently, including in the US. BA.1 seems to have increased transmissibility but lower severity, although as we've seen it can still stretch our healthcare resources beyond capacity. It exhibits immune escape in terms of infection, though vaccine and natural immunity still provide good to excellent protection against severe disease, depending on individual circumstances.

The subvariant BA.2 (B.1.1.529.2) is a bit in the spotlight now, comprising a few percent of US cases as we hold our breath to see if it precipitates another infection wave. BA.2 certainly has a faster replication rate than BA.1 and likely is more transmissible. Although cases have been reported throughout the world, it's still a bit early to judge relative severity.

BA.3 is much less common so far. Its spike protein mutations aren't that different from BA.1 and BA.2; much remains to be learned about its ability to spread and cause severe disease.

NPI relaxation across the US leads us into a new era of the pandemic. We'll see what this experiment reveals in the coming months.

Roller Coaster Week

Bud WiedermannFebruary 13, 2022Leave a comment

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.

6 More Weeks of Winter

Bud WiedermannFebruary 6, 2022Leave a comment

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.

Month: February 2022