People who had COVID-19 had greater risk of blood clots, lung disease, fatigue, and diabetes for up to two years
 
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In May 2023, WHO declared the emergency phase of the pandemic to be over. While COVID-19 lingers in waves, its impact has lessened. Focus is now shifting to the continued health of those who survived the initial infection. The influence of COVID-19 on blood vessels, heart, and nervous system raises concerns about delayed health issues.

Being a new disease, time is needed for definitive answers. Analysing large amounts of data can unveil hidden trends — the link between smoking and cancer, for instance, was established only when large groups of smokers and non-smokers were compared. COVID-19 is no different. Many people who survive COVID-19 and feel fine may conclude that it is just a common cold, which is not true.

Three studies published this month have addressed this issue. They looked at large databases of people who had COVID-19 and followed up for one to two years.

The Washington University/VA St. Louis Health Care System group looked at 1,38,818 people who survived COVID-19, among whom 20,580 were hospitalised. Those who were initially hospitalised experienced more problems afterwards when compared with people who were not infected. They had higher death rates, hospitalisation and other health problems for at least two years. In comparison, the deaths rates among those who had COVID-19 but did not require hospitalisation was higher but only for the initial six months.

However, the risk of other health outcomes including hospitalisation persisted. The risk of Long COVID, an assorted group of health conditions, persisted for two years. This was more marked in the hospitalised group than the non-hospitalised group. Among 80 health conditions that comprise Long COVID, 65% conditions persisted at two years in the hospitalised group, while 31% persisted in the latter. Compared with uninfected individuals, those who had prior COVID-19 had greater risk of blood clots, lung disease, fatigue, digestive ailments, muscle and joint problems and diabetes for up to two years. Significant amount of disability occurred, 25% of which was reported in the second year. The findings are published in Nature Medicine.

A study in JAMA compared over 0.2 million people who had survived COVID-19 with over one million people who were uninfected. The difference in death rates between the two groups was stark. At the end of two years, 8.7% of those who had prior COVID-19 had died compared with only 4.1% in the other group. The rate of death was highest in the initial few months. Among those who survived the first six months, the death rate declined afterwards, unexpectedly dropping below the average death risk of the comparison group.

The reason for this apparent drop could probably be a phenomenon called the ‘depletion of susceptibles’ in the COVID-19 group — the initial period killing those who were more likely to die. The relatively healthier individuals who survived had a lower death rate than the comparison group. Close healthcare monitoring too might have also prevented a few deaths.

An ICMR study looked at 14,419 people who survived COVID-19 hospitalisation, revealing a one-year death rate of 6.5%. New or persistent symptoms of post-COVID condition such as fatigue, breathlessness and memory problems lasting four-eight weeks were present in 17% of the patients. Death during follow up was more common among such individuals. Those who had prior vaccination had lower death risk.

These large studies underscore the need to reduce the risk of infection, particularly during surges.

(Rajeev Jayadevan is co-chairman of the National IMA COVID Task Force)