17 March 2022 Blog Post: On BA.2
News from England and Germany suggests that the BA.2 variant (the so called “stealth subvariant”) is causing a significant uptick in cases in Europe. According to a MSNBC article, “
Covid cases have increased dramatically in the U.K. in recent weeks, and Germany continues to mark record high daily infections with more than 250,000 new cases a day.”
When looking at an epidemic curve, however, the numbers tell a somewhat different story (Figure 1 below). Indeed Germany is reporting a significant number of cases (about 225 new daily cases per 100,000 – for comparison Omicron topped out at 453 new daily cases per 100,000 here in Los Angeles County). I’ve added recent LA County case data as Figure 2 below But notice that Germany did not experience the Omicron surge seen in both the US and UK with cases rising through December and peaking in early January. The BA.2 is Germany’s Omicron.
A totally different phenomenon is occurring in the UK which has lifted all COVID restrictions, to the extent that British Airways is no longer requiring masks on airplanes. The curiously named ‘Living with COVID’ plan was implemented as a “moment of pride” on February 21st (link: https://www.cnbc.com/2022/02/21/uk-pm-boris-johnson-to-lift-all-remaining-covid-restrictions-in-england.html). In addition to rescinding mask mandates, there is no longer a requirement for individuals who test positive to self-isolate. Previously free of charge rapid antigen tests (or in UK parlance, lateral flow tests) will be phased out as well. So, in essence, a functioning test/trace/isolate policy has not just been scrapped – instead replaced with a test and no-isolate policy.
Another concerning aspect of the UK policy shift is the timing. Returning again to Figure 1 below, note that UK case rates were significantly higher than those of the US when the policy was enacted at about 40 new daily cases per 100,000 (as a reference, the case rate in Los Angeles County that week was 19.9). Unsurprisingly case rates have risen and are now at 125 new daily cases per 100,000 while Los Angeles County has continued to fall and are down to 8 new daily cases per 100,000.
Figure 1: Incidence rates of COVID-19 infection in US, UK and Germany. Mid-November 2021 through mid-March 2022.
So, in summary, the comparisons to be make with the UK or Germany experience are not strictly applicable to the US at this point in time. Germany, most certainly not, as they are just now experiencing the Omicron outbreak which consumed the US more than two months ago. They just happen to be having that experience with BA.2 rather than the original Omicron.
The US now has similarly rescinded mask mandates broadly, a move that has the potential to increase case rates. On the other hand, there has been no removal of the good public health policy to isolate for at least 5 days when one has a positive test. This well balanced article from NPR summarizes what we might expect (link: https://www.npr.org/sections/health-shots/2022/02/21/1081810074/omicron-ba2-variant-spread). Put simply:
“A lot of us were assuming that it was going to quickly take off in the United States just like it was doing in Europe and become the new dominant variant,” says Nathan Grubaugh, an associate professor of epidemiology at the Yale School of Public Health.
So far that hasn’t happened.
Figure 2: Incidence rates of COVID-19 infection in Los Angeles County, California. Mid-November 2021 through mid-March 2022.
𝗦𝗶𝗴𝗻 𝗨𝗽 𝗳𝗼𝗿 𝗢𝘂𝗿 𝗡𝗲𝘄𝘀𝗹𝗲𝘁𝘁𝗲𝗿