Scientist in lab with COVID-19 equipment
© Cristobal Vicent

Academic Research Scholar, Prof Wendy M. Purcell, provides an update on COVID-19, communicable disease and immunology

Throughout 2022, we’ve come to learn more about COVID-19 in relation to subvariants, the inclusion of children from six months in vaccination programmes and concern about post-COVID effects and communicable diseases on health and well-being.

COVID-19 and vaccines

COVID-19, like all viruses, is an intracellular parasite that makes use of its host cells’ replication machinery to make copies of itself. With each copy, the virus can change or mutate, so that over time we see variants emerge. The characteristics of the variants can be different from the original virus (known as the ‘wild’ type). This is the way a virus ‘survives’ in a population, often despite our best efforts to combat it. Some of the COVID-19 variants never hit the headlines, while others, such as Delta and Omicron, were responsible for the various ‘waves’ of the outbreak we saw. Omicron was more transmissible than Delta and now has its own variants, with subvariants BA.5 and BA.4 responsible for many cases in the summer of 2022.

There still seems to be some misunderstanding about the vaccines. However, people talk about getting COVID-19 despite being vaccinated. So, let us be clear that the vaccine does not prevent a person from becoming infected, and so far, they seem to be holding against the variants and subvariants. But the COVID-19 vaccines are safe (1) and do protect people from severe illness, hospitalisation or death from the virus – albeit they appear somewhat less effective (2) against some of the subvariants (3). It is, therefore, worth adopting the layered approach (4) we recommended to the airlines at the height of the pandemic. That is, mitigating the risk of infection in crowded places or if you have concerns, by wearing a face mask, practising hand hygiene, maintaining social distancing and good ventilation. It also means keeping up to date with vaccine boosters as recommended, given that immunity wanes over time. The boosters do what they say – boost our immunity, so we can be in a good state of readiness to fight the virus should we become infected.

COVID-19 vaccine development © Cristobal Vicent
© Cristobal Vicent


Common to many viral infections, a period of fatigue can accompany recovery and may last a while thereafter. With COVID-19, however, there are reports of fatigue (5), sometimes accompanied by other symptoms (6) being experienced long after the infection subsides. Termed ‘long-COVID’ (7) by sufferers, it is now the subject of intense clinical interest given reports variously claim up to one in twenty, one in ten, one in five or even one in two people may experience some symptoms of it; some studies suggest the risk in vaccinated people is lower. Trials (8) and clinical studies (9) on long-COVID are being conducted in the UK. Drug trials (10) are targeting fatigue, ongoing respiratory complications, so-called ‘brain fog’ (11) and other reported symptoms in certain groups, including children. (12)

As we learn more about the basic science of the virus SARS-CoV-2 that causes the infectious respiratory communicable disease COVID-19, some of these post-viral symptoms are starting to make more sense (13). Several research groups hold that the formation of micro-clots is responsible for both the respiratory and cognitive symptoms documented in long-COVID. Others disagree and suggest that the virus persists in the body, causing harm to various systems, including the gut, brain and lungs. This may cause the immune system to be triggered over time, leading to chronic inflammation that, in turn causes harm to the body. It is clear then that there is more still to discover.

COVID-19 research/immunology

Worldwide, scientists and clinicians continue to explore COVID-19, from the biology of the virus through to clinical trials and community surveillance. We know a lot already, including that this multi-pronged global effort has brought down the fatality rate significantly, especially among the elderly. However, given unequal access to vaccines and drugs remains, we can expect COVID-19 epidemics to continue in the period ahead.

Contributor Profile

Research Scholar
Harvard T.H. Chan School of Public Health, University College London’s Global Business School for Health
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