Covid-19: Omicron sub variants driving new wave of infections in UK

Admissions rising

Latest data from NHS England show that hospital admissions with covid are rising sharply across England, up 31% week on week. Admissions rose by between 20% and 42% in all English regions.2

The total number of beds occupied by confirmed covid-19 cases in English hospitals was 5008 on 16 June, up from a low of 3800 on 1 June. This is far lower than in April, however, when there were over 16 000 beds occupied. The intensive care unit and high dependency unit admission rate remained low in the week ending 12 June 2022.

The current rate of increase in hospital admissions is faster than seen during the BA.2 omicron wave in March. John Roberts, an actuary and member of the covid-19 actuaries response group, wrote on Twitter, “So whilst the current level of admissions is still below the lowest level between the BA.1 and BA.2 surges, it’s the current rate of growth that should be of concern.”

Deepti Gurdasani, senior lecturer at the William Harvey Research Institute, Queen Mary University of London, told The BMJ, “I am concerned about the current wave. This is our second wave in six months, and infection has remained very high even between waves.

“It’s hard to predict how large the wave will be but, given where we are in terms of NHS pressure and long covid impact, any increase at this point from a high baseline will put further pressure on an NHS that’s already struggling to provide safe and urgent patient care, and will likely continue to lead to even higher levels of long covid.”

NHS England medical director Steve Powis told the Health Service Journal3 that he expects fewer admissions during the new covid wave than the previous two 2022 surges, but he added, “We are likely to see a bit of an increase over the next few weeks.”

Saffron Cordery, the interim chief executive of NHS Providers, said NHS trust leaders were monitoring the situation closely. “We are, thankfully, nowhere near the peaks seen during the worst of the pandemic. But if admissions go up dramatically because of a new wave of infections caused by new omicron variants this summer, the NHS may have to take its foot off the recovery accelerator and divert efforts and capacity into looking after people with covid once again. Clearly we all want to avoid this happening.”

The impact of sub variants

The ONS says the increase in people testing positive is “likely caused by infections compatible with omicron variants BA.4 and BA.5.” Latest data from the Covid-19 Genomics UK Consortium show that BA.4 and BA.5 are now at 50% of sequenced cases in England.4

On 20 May BA.4 and BA.5 were officially designated as variants of concern in the UK. BA.4 and BA.5 became dominant in South Africa and their wave has now passed with fewer hospital admissions and deaths than their BA.1 wave in December. In Portugal BA.5 is now dominant but their wave looks to have just peaked.

An increase in the proportion of BA.4 and BA.5 infections has also been observed in other European countries. On 13 June the European Centre for Disease Prevention and Control warned, “The growth advantage reported for BA.4 and BA.5 suggest that these variants will become dominant throughout the EU and EEA, probably resulting in an increase in covid-19 cases in coming weeks.”5

Writing in The BMJ, Christina Pagel, professor of operational research at University College London, said, “We will be the first (but not the last) major country to have a BA.4.5 wave after having had two previous omicron waves. This means that we might get some additional protection from the high number of infections we had in March which will reduce the size of this coming wave. Nonetheless, a significant proportion of the country will get sick, especially as boosters are waning.”6

Omicron shows a growth advantage compared with earlier variants. And new data published this week78 show that it also appears to be good at evading the immune system, so even infection with omicron does not induce particularly good immunity against future infection with this variant.

Pagel added, “While omicron might be somewhat less severe than delta, and people have higher immunity through vaccination and previous infection, it is not mild. At a population level, its sheer transmissibility more than compensates for any reduction in experienced disease severity or symptoms for the individual.”