Issue #105: Long COVID and Omicron: the UK data

Written by Nobel Laureate Professor Peter Doherty

As physicians and research scientists probe the pathogenesis (how the disease works in our bodies) of COVID-19, perhaps the biggest ‘black hole’ relates to the spectrum of persistent debility we call Long COVID (LC). Treating this complex LC ‘syndrome’ is obviously difficult if clinicians don’t understand the physiological basis of what’s going on. Currently, it is a very confusing area.

Over the next few weeks, my intent is to find out as much as I can about LC by reading published material and communicating with colleagues, then summarize what I’ve found in this series. One thing is certain: any attempted synthesis at this stage will, at best, be a 'work in progress'. Rather than begin at the beginning and develop the LC story systematically from a ‘bottom-up’ of case definition and possible disease mechanisms, I thought I’d go first to the question so many are asking – can we develop LC after being infected with an Omicron variant of SARS-CoV-2?

So far as I can find out, the best available information on the incidence of LC following Omicron infection comes from UK National Health Service (NHS) data sets published by their Office of National Statistics. Here’s the range of symptoms that they identify as being characteristic of LC: https://www.nhs.uk/conditions/coronavirus-covid-19/long-term-effects-of-coronavirus-long-covid/. In fact, the list does not look all that different from the ‘myalgic encephalitis/chronic fatigue syndrome’ (ME/CFS) spectrum that has long frustrated both doctors and patients. If we can understand LC, it seems likely that we will also define at least some of the basis of ME/CFS.

Like our Medicare, the NHS provides universal health coverage. While the Australian system is, from the comments of informed people who have looked at this seriously, one of the best in the world when it comes to accessibility and outcomes, the fact that healthcare delivery is a matter for the States in our federated system means that we are not (in comparison to the UK where the NHS has oversight and control) so great when it comes to efforts like National Surveys. The current population of the UK is around 68.5 million (about 2.7 times that of Australia), so they have a bigger pool to draw from and they’ve had a much longer experience of large numbers of people with COVID-19.

The conclusions summarized below are from UK reports of May 6, 2022. The analysis is for people aged 18 or older (about 80% of the population) in socio-demographically similar groups, who are living in private households rather than communal settings, like prisons or aged care homes. The subjects self-reported and had persistent symptoms at 4-8 weeks or more beyond a positive PCR test for SARS-CoV-2 infection. All comparisons are following a first infection. Reinfections, which are more common with Omicron, are excluded.

Looking at the numbers collected from April 2020 when the survey began, some people have reported debilitating LC symptoms for as long as one (744,000) or two (235,000) years. The situation in April 2022 was that 1.8 million people, or 2.8% of the relevant UK population, were currently experiencing symptoms of LC contracted at one or other time throughout the pandemic

Any comparison for the Delta and the Omicron BA.1 and BA.2 variants uses data collected between May 17, 2021 (when the first Delta cases were recorded) and those who were positive by PCR before April 17, 2022. Omicron BA.1 displaced Delta and was the dominant strain by 13 December, giving way to Delta BA.2 by 24 January. When it comes to the statistics of first reporting LC: 446,000 first did so after contracting Delta, and 438,000 after Omicron.

Comparable to the situation in Australia until some started to receive Novovax, all results are for people given the AstraZeneca, Pfizer or Moderna vaccines. In double vaccinated adults, the prevalence of LC reported 4-8 weeks after PCR diagnosis was 15.7% for Delta and 8.7% for Omicron BA.1. That statistically significant difference disappeared for those who were triple vaccinated, with the incidence being 8.5% for Delta and 8.0% for Omicron BA.1. Comparing Omicron BA.1 and BA.2 in triple vaccinated participants, the figures were 7.8% and 9.3% respectively.

The statistical analysis in this report is described as ‘experimental’, meaning presumably that the numbers will be further refined, and is ‘adjusted’ for socio-demographics, timing of vaccination, and other parameters. But these findings do make one thing very clear: that even triple vaccinated people can develop LC after Omicron infection. It’s too soon, of course, to come to any conclusions about the duration and continued severity of LC following Omicron in vaccinated or unvaccinated subjects.

We do know that three, or better four (for older people), doses of vaccine are helping to keep people out of hospital, but has vaccination provided protection against the worst forms of LC following infection with Delta or Omicron?

Next week we’ll discuss what we do know about vaccination, LC and COVID-19, especially with regard to some of the complexities associated with answering that question for Omicron.