The delta variant remains the dominant and most significant coronavirus strain of concern in Michigan and throughout the country, though you may have heard about another new strain gaining ground.
Last week, the World Health Organization added the Mu variant, also known as B.1.621, to its list of “variants of interest.” The strain was first discovered in January 2021 in Columbia, and has since been found in 49 states - all but Nebraska - as of earlier this week.
Health officials note that the Mu variant evolved several potential properties of immune escape, meaning it could potentially evade protection provided by natural infection or vaccination. But more research is needed to better understand the strain and how effective the available vaccines are against it.
In Michigan, there have been 10 known COVID-19 cases linked to the MU variant as of Sept. 3, according to the Department of Health and Human Services. There could be more cases, as not all positive samples are sequenced, but the variant is believed to make up fewer than 1% of current cases.
Among those 10 cases, none of the individuals reported any international travel. Two required hospitalization, two were breakthrough infections, and six reported symptoms, according to MDHHS.
Dr. Liam Sullivan, an infectious disease specialist at Spectrum Health in Grand Rapids, noted that the Mu variant seems to be as transmissible as delta. Vaccines appear to protect against severe disease from the newest variants as well as the older ones, but these studies are “very, very early.”
Sullivan said there is always concern the new variants could escape vaccine-induced immunity.
“I mean that’s something we always have to watch, and I think that’s more reason why people need to get vaccinated because we need to slow the spread of this virus down,” he said.
As of Tuesday, Sept. 7, about 61% of Michigan residents 12 and older had gotten a first dose of vaccine, and 56.2% had been fully vaccinated. Health officials estimate that more than 70% of the public needs to be vaccinated to slow the coronavirus mutations. Some estimate the threshold is closer to 80% or 90% vaccination to reach a level of widespread community protection.
Dr. Russell Lampen, infectious disease specialist at Spectrum, said he is not aware of any mu cases in West Michigan.
“We are essentially 100% delta variant in West Michigan,” Lampen said, noting that the variant remains the “big player” in viral transmission heading into this fall.
The delta variant has an “uncanny ability” to attach to cells in respiratory tracts tighter than previous variants, which gives it the ability to replicate faster and into more significant levels, Sullivan said.
As of Sept. 3, Michigan had 1,806 cases linked to the delta variant, which has represented 99.3% of specimen sequenced over the last four weeks. The delta variant has been discovered in 74 of 83 counties.
Vaccines are slightly less effective against the delta variant, but still highly effective. A Public Health England study found the Pfizer vaccine, the most commonly administered vaccine in Michigan, was 88% effective among those with the delta variant. This compared to 95% effective against the alpha variant. An Israel study found it had a lower efficacy – 64 percent, noted Dr. Matthew Sims, director of Infection Prevention Research for Royal Oak-based Beaumont Health.
The CDC has not listed the Mu variant as one of its “variants of concern.” There are four of those, including the B.1.1.7 strain (alpha) first discovered in the U.K., the B.1.351 strain (beta) first discovered in South Africa, the P.1 strain (gamma) first discovered in Japan and Brazil, and B.1.617.2 (delta) first identified in India.
Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said health officials are maintaining a “close eye” on the mu variant despite it being “not at all even close” to becoming the dominant COVID-19 strain in the U.S.
Meanwhile, the World Health Organization is also monitoring the C.1.2 variant, which was first identified in South Africa in May. It is neither considered a variant of concern, nor a variant of interest as of Sept. 10.
There have been no C.1.2 cases reported in Michigan to date.
Vaccines are readily available at local pharmacies, health systems, clinics, and health departments. To find a vaccine near you, visit Michigan’s COVID-19 vaccine website or go to VaccineFinder.org.
Read more on MLive:
Threat of fourth COVID surge in Michigan hospitals is ‘very real’ without more vaccinations
Weighing the risks of COVID vaccines against the risk of the COVID virus
Michigan researchers estimate combined vaccination, natural immunity rate
What we know at this point about natural immunity to COVID-19
Ad Choices