BA.5 Omicron is Becoming Dominant in Europe

In the EU/EEA, countries have been detecting low proportions of the SARS-CoV-2 variants BA.4 and BA.5, but many have seen an increase in recent weeks. This suggests that the variants will become dominant throughout the EU/EEA, probably resulting in an increase in COVID-19 cases.

The European Centre for Disease Prevention and Control has warned that countries should remain vigilant for signals of BA.4 and BA.5 emergence and spread, and strengthen sentinel surveillance systems.

The extent of the increase in COVID-19 cases will depend on various factors, including immune protection against infection influenced by the timing and coverage of COVID-19 vaccination regimes, and the extent, timing and variant landscape of previous SARS-CoV-2 pandemic waves.

Based on limited data, there is no evidence of BA.4 and BA.5 being associated with increased infection severity compared to the circulating variants BA.1 and BA.2. However, as in previous waves, an increase in COVID-19 cases overall can result in an increase in hospitalisations, ICU admissions and deaths.

The European Centre for Disease Prevention and Control has issued a warning that countries should remain vigilant for signals of BA.4 and BA.5 emergence and spread; maintain sensitive and representative testing and genomic surveillance with timely sequence reporting, and strengthen sentinel surveillance systems (primary care ILI/ARI and SARI). Countries should continue to monitor COVID-19 case rates – especially in people aged 65 and older – and severity indicators such as hospitalisations, ICU admissions, ICU occupancy and death.

Improving COVID-19 vaccine uptake of the primary course and first booster dose in populations who are yet to receive them remains a priority. It is expected that additional booster doses will be needed for those groups most at risk of severe disease, in anticipation of future waves.

The SARS-CoV-2 variants BA.4 and BA.5 were first detected in South Africa in January and February 2022, respectively. They became the dominant variants in that country in May 2022
In Europe the BA.4 and BA.5 Omicron variant was first detected in March 2022. Portugal was the first country in the EU/EEA to observe a significant increase in cases and in the proportion of one of these two variants (BA.5).

As of 30 May 2022, BA.5 is the dominant SARS-CoV-2 variant in Portugal, with an estimated proportion of around 87% [6,14]. Between week 19 and 20, 2022, case numbers in Portugal declined and became stable, indicating that the peak of a BA.5 wave in Portugal may have been reached.

Antibodies produced by 15 individuals previously immunised against COVID-19 that had then contracted the BA.4 and BA.5 Omicron variant were more effective than those from people who had recovered from natural infection alone.

So far there is no indication that BA.4 or BA.5 are associated with new symptoms or more severe disease. This is to be expected, given that the majority of mutations are similar to those found in other Omicron lineages, although it something that will continue to be closely monitored by the WHO and local health teams.