I see Covid is back in the news. Why so?

The first Irish cases of a new variant, BA.4, were detected earlier this month. Just two of them, but the number of cases that are genetically sequenced at present is very low so there may be more.

What’s the story with BA.4?

BA.4 is another variety of the Omicron variant which has been dominant in the State since early spring. We started with BA.1, then BA.2 came along and had a growth advantage that led to it becoming dominant. In January and February scientists in South Africa spotted two new subvariants of Omicron, BA.4 and BA.5, which have gone on to become dominant there. So far, no cases of BA.5 have been identified in Ireland.

Is there lots of BA.4 in Europe?

By late April the UK authorities had concluded there was evidence of international spread of BA.4 and BA.5, including small numbers of cases in the UK and rest of Europe. So far, 115 cases of BA.4 and 80 cases of BA.5 have been detected in the UK. Cases are also rising in Portugal and Austria.

So what is happening?

BA.4/BA.5 have a growth advantage over the existing strains circulating so they are starting to take over, scientists reckon. The European Centre for Disease Control (ECDC) has recognised them as distinct entities, and labelled them variants of concern. But because Covid-19 incidence is falling and the summer is coming, it is likely they will take longer to become dominant than Omicron did earlier this year.

Should we be worried?

Chief medical officer Dr Tony Holohan says the two strains have a growth advantage most likely because they can evade immunity provided by prior infection and vaccination, particularly as this wanes over time. However, there is no indication they are any more severe than previous Omicron lineages.

One worry is that people can get reinfected, even those who had Omicron recently. Vaccines still protect against serious illness but their ability to protect against infection will keep waning with time. Repeated infections could result in more long Covid cases.

Some scientists are predicting a surge in cases as BA.4/BA.5 spreads, but do not expect it to be as large as the original Omicron wave.

The ECDC has warned the variants “could cause a significant overall increase in Covid-19 cases in the EU/EEA in the coming weeks and months”.

What is going to happen to the pandemic now?

It is hard to know how much disease is out there because we are not testing as much as before. Covid-19 hasn’t gone away – about 34,000 PCR and antigen tests were reported last week and one in eight was positive.

The impact on the hospital system is relatively small now, there are 230 people with Covid in hospital, including 28 in intensive care, and half of these are incidental cases.

A rise in BA.4/BA.5 could fuel an increase in cases but with the protection afforded by vaccines there is unlikely to be significant pressure on the hospital system. That could change in the autumn, with or without the arrival of a new variant.

Will there be new vaccines to protect us?

Most likely. Second boosters are being provided to over-65s but it seems unlikely they will be recommended for the general population in the short term.

In the US policymakers in the Food and Drug Administration are expected to decide in July what type of vaccine to offer this autumn, similar to the way the flu vaccine is reformulated to counter the most prevalent strains each year.

They’ll probably be trying to get the maximum length and duration of protection from these next-generation vaccines so that people don’t have to get boosters every few months.

Of course the virus could mutate further, and in a harmful way, and frustrate their best intentions.

The Irish Times

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