Weekly COVID New Hospitalizations
#17,739
Given the relative lack of reporting these past few months, one could be forgiven for believing the COVID threat has passed, but the SARS-CoV-2 virus continues to simmer - and evolve rapidly - around the globe.
Most countries - in an attempt to `move on' from the pandemic - have intentionally scaled back their testing and reporting (see No News Is . . . Now Commonplace). As a result, the picture we get doesn't necessarily represent reality.
The World Health Organization - faced with dwindling data - moved to monthly Epidemiological reporting on COVID at the end of September. Their latest update (Edition 160) was published yesterday.
While they report:
Globally, the number of new cases decreased by 42% during the 28-day period of 25 September to 22 October 2023 as compared to the previous 28-day period, with over half a million new cases reported. The number of new deaths decreased by 43% as compared to the previous 28-day period, with over 4700 new fatalities reported. As of 22 October 2023, over 771 million confirmed cases and over six million deaths have been reported globally.
There is an important caveat. Only 18% of the world's nations (n=41) reported ICU admission data in the last month (at least once), and of those, only 22 nations (9%) reported consistently.
The WHO report warns:
Reported cases do not accurately represent infection rates due to the reduction in testing and reporting globally. During this 28-day period, only 40% (93 of 234) of countries reported at least one case to WHO – a proportion that has been declining since mid-2022.
It is important to note that this statistic does not reflect the actual number of countries where cases exist. Additionally, data from the previous 28-day period are continuously being updated to incorporate retrospective changes in reported COVID-19 cases and deaths made by countries.
Data presented in this report are therefore incomplete and should be interpreted considering these limitations. Some countries continue to report high burdens of COVID-19, including increases in newly reported cases and, more importantly, increases in hospitalizations and deaths – the latter of which are considered more reliable indicators given reductions in testing.
Even the 10% of countries that are reporting regularly have scaled back testing and reporting, and so comparisons to what was being reporting a year ago are difficult to make.
While we don't appear to be seeing huge numbers of cases in the United States right now, numbers in Europe and Southeast Asia are increasing. Meanwhile, we get zero information out of China, and very little from Africa or the Eastern Mediterranean regions.
This lack of surveillance is a concern because the SARS-CoV-2 virus continues to evolve at a rapid rate, and new - and unpredictable - variants continue to emerge. A little over two months ago we saw the emergence of a new `branch' on its family tree (BA.2.86) which boasted the biggest antigenic change since Omicron.
A detailed report on the rates of evolutionary changes in endemic human viruses appeared last week in Cell Host & Microbe (excerpt below) which finds SARS-CoV-2 to be evolving at more than twice the rate of influenza A/H3N2.
An atlas of continuous adaptive evolution in endemic human viruses
Kathryn E. Kistler 3, Trevor Bedford
Open Access Published: October 24, 2023 DOI: https://doi.org/10.1016/j.chom.2023.09.012
Highlights
• Ongoing adaptive evolution in human endemic viruses is largely in surface proteins
• Immune evasion drives continuous adaptive evolution in many endemic human viruses
• Antigenic evolution occurs in several viral families
• SARS-CoV-2 is accumulating protein-coding changes faster than other endemic viruses
Summary
Through antigenic evolution, viruses such as seasonal influenza evade recognition by neutralizing antibodies. This means that a person with antibodies well tuned to an initial infection will not be protected against the same virus years later and that vaccine-mediated protection will decay. To expand our understanding of which endemic human viruses evolve in this fashion, we assess adaptive evolution across the genome of 28 endemic viruses spanning a wide range of viral families and transmission modes. Surface proteins consistently show the highest rates of adaptation, and ten viruses in this panel are estimated to undergo antigenic evolution to selectively fix mutations that enable the escape of prior immunity. Thus, antibody evasion is not an uncommon evolutionary strategy among human viruses, and monitoring this evolution will inform future vaccine efforts. Additionally, by comparing overall amino acid substitution rates, we show that SARS-CoV-2 is accumulating protein-coding changes at substantially faster rates than endemic viruses.
This rapid evolution has led to tremendous diversity among COVID variants. A year ago the CDC was tracking 1 hugely dominant strain (BA.5 at 68%), and a half dozen `contenders', but today they are tracking more than 30 variants in circulation in the United States alone, and no variant has captured more than a 25% share since early summer.
That trend could be about to change, as the latest CDC Nowcast (below) shows variant HV.1 doubling over the past 4 weeks, while EG.5 is starting to lose ground. Further back in the pack, HK.3 also appears to be gaining, but it remains to be seen which of these variants will prevail.
As mentioned earlier, a new and antigenically distinct variant (BA.2.86) has appeared, and while it doesn't show up yet on the CDC's Nowcast, it - and a close relative JN.1 - are being closely monitored.
It isn't known whether they can successfully compete with the XBB lineage of variants, or even what their impact might be if they were to spread widely.
But they are a reminder that COVID continues to evolve, and we can't afford to become complacent, even if we aren't hearing about the virus as much as we used to.
As we've seen often in the past, no news isn't necessarily good news.
