Two new ‘variants of concern’ spreading in Europe
TWO new Covid strains have been designated as “variants of concern” amid signs they can dodge immune protection, including reinfecting people who previously had Omicron infections.
The variants – known as BA.4 and BA.5 – were first detected in South Africa in January and February respectively, and have since become the dominant strains in the country.
It is the first time since Omicron emerged at the end of November that a new variant has been classified as a variant of concern.
According to the World Health Organisation, BA.4 has been detected in at least 16 countries and BA.5 in 17 countries. Both have been identified in small numbers in the UK.
BA.5 has constituted an increased proportion of cases in Portugal in recent weeks, with the Portuguese National Institute of Health estimating the strain already accounted for approximately 37% of positive cases by May 8.
It is expected to become Portugal’s dominant variant by May 22.
Scottish Government epidemiologists previously
warned that holidaymakers returning from abroad this summer were likely to seed a new Covid wave.
The European Centre for Disease Prevention and Control (ECDC) said preliminary studies “show a significant change in antigenic [immune response] properties of BA.4 and BA.5 compared to BA.1 and BA.2, especially compared to BA.1”.
The original Omicron strain that spread in the UK in the run-up to Christmas is known as BA.1, but it has since been overtaken by the sublineage
BA.2, which drove the most recent Covid wave in the UK.
The ECDC said BA.5 is estimated to have a “growth advantage” of about 13% over
BA.2; the growth advantage of BA.4 has not yet been quantified.
However, in both cases their ability to spread faster than BA.2 is believed to be driven by “their ability to evade immune protection induced by prior infection and/or vaccination, particularly if this has waned over time”.
There is no indication at this stage they cause more severe disease.
The ECDC said “limited available data” from laboratory studies suggests individuals who are unvaccinated but previously recovered from an Omicron infection “are unlikely to be protected against symptomatic infection with BA.4 or BA.5”.
Vaccinated individuals appear to have better protection, but this is also likely to wane.
Overall, the ECDC predicts BA.4 and BA.5 will drive fresh Covid waves in Europe over the summer.
It states: “The presence of these variants could cause a significant overall increase in Covid-19 cases in the EU/EEA in the coming weeks and months.
“The overall proportion of BA.4 and BA.5 in the EU/EEA is currently low but the high growth advantages reported suggest that these variants will become dominant in the EU/EEA in the coming months.
“Based on the limited data currently available, no significant increase in infection severity compared to the circulating lineages BA.1 and BA.2 is expected.
“However, as in previous waves, if Covid-19 case numbers increase substantially, some level of increased hospital and ICU admissions is likely to follow.
“ECDC encourages countries to remain vigilant for signals of BA.4 and BA.5 emergence.
“Early variant detection critically relies on sensitive and representative testing and genomic surveillance, with timely sequence reporting.”
It comes after the World Health Organisation’s chief executive, Tedros Adhanom Ghebreyesus, warned that a substantial reduction in Covid testing globally was leaving the agency “increasingly blind to patterns of evolution and transmission” of the virus.
Scotland ended routine PCR testing – which is required for sequencing of variants – on May 1.
The ECDC said a second booster may be necessary for all over-60s.
In the UK, a second Covid booster is already being offered to all adults over 75.
A separate new Covid strain – BA.2.12.1 – has so far been detected in 23 countries, and is spreading rapidly in the United States. It is already the dominant strain across New York and
New Jersey.
During an online Q&A, the WHO’S technical lead on Covid, Maria Van Kerkhove, said she expected to see an increase in case detection of BA.2.12.1 worldwide due to its higher growth rate over BA.2, but stressed there was also no evidence it caused more severe disease.
She urged governments across the world to closely monitor BA.2.12.1, BA.4, and BA.5, adding: “We talk to government all the time about the need to maintain the surveillance systems so that we can track this, we can trace it, and we can assess it in real time.”