I often find that a person’s response to Covid-19, especially in the current climate when we have announced a “move to endemic” phase, is often related to how much of the evidence they read about Covid-19.

One poorly discussed issue, regarding our Covid-19 risk, is the serious effect of Long Covid and the long-term health impacts (post-Covid conditions) of a Covid-19 infection.

There is a growing body of evidence that needs our attention. Allow me to summarise some of the evidence that is already available.

Although individual research may be limited in size, put together the collective work should make us sit up and take note of this health threat.

I am indebted to Stephen Reicher, Professor of Social Psychology at the University of St Andrews in the UK, for some of the ideas and links in this article.

How common is Long Covid and does vaccination help?

There is limited data locally on Long Covid, although the Health Ministry (MOH) has information on its website.

A MOH press statement in February 2022 stated that 10% to 15% of those infected with Covid-19 have Long Covid. International data suggest that the problem is much larger.

A meta-analysis and systematic review published in April 2022, that combined data from 50 international studies, suggests that the worldwide prevalence of Long Covid (post Covid-19 conditions) is 43%.

The rate in hospitalised patients was 54% and in non-hospitalised 34%. In this review, rates of Long Covid were highest in the Asian studies.

There are fewer studies on the Long Covid risk after an asymptomatic infection, but data is emerging that 20% to 30% of asymptomatic infections may result in persistent symptoms.

Some studies show vaccination reduces the risk of Long Covid by approximately 50%, however, it does not remove the risk completely.

What is the impact of Long Covid on the brain, heart and other organs?

A detailed UK study (published in April) looking at individuals who received critical care for Covid-19 compared with matched controls showed persistent cognitive impairment (average loss in IQ of 10 points) six to 10 months after admission with only gradual recovery.

A large longitudinal cohort study for one year (over 1,400 participants with a control group), from Wuhan, China (published in March) showed that 12% of survivors had cognitive impairment 12 months after discharge.

The risk was higher for individuals with severe cases, those with non-severe Covid-19 had a risk of early-onset cognitive decline.

A meta-analysis and systematic review (published in March) looking at changes in cognitive functioning after Covid-19, summarised data from 27 studies involving more than 2,000 persons.

Impairment in executive functions, attention, and memory were found in post-Covid-19 patients compared with healthy controls.

One study showed 0.5% to 2% brain shrinkage after infection compared with before the pandemic, even in mild infections.

A large study from the US (published in February) looked at more than 150,000 individuals with Covid-19 and compared their cardiac risks with controls one year later.

They conclude: “Our results provide evidence that the risk and one-year burden of cardiovascular disease in survivors of acute Covid-19 are substantial.

“These risks and burdens were evident even among individuals who were not hospitalised.”

The risk was two to three times higher for those infected to get strokes, arrhythmias, ischemic heart disease, pericarditis, heart failure and clots (thromboembolic disease) one year after the infection.

There is increasing evidence suggesting there is an increased risk of diabetes after a Covid-19 infection, both in non-hospitalised and hospitalised patients (higher in those with severe Covid).

More data and studies can be quoted, but I hope the point is clear, that Long Covid is not mild and may have long term health consequences.

This impact is not just for those hospitalised but includes asymptomatic infections. Children are also not spared.

Many scientists now speak of the burden of disability that will come with this pandemic.

What then should we do?

The aim of sharing this is not to instil a sense of fear or dread about the future but to inform us about our risks. The declaration of a “move to endemic” has made many relax.

Others who do not read the science and data are ignorant of the risks and even deride those who are more careful.

What is required is a measured, careful approach that keeps our family safe while we continue with the needs of work, school and leisure.

Some suggestions for us to consider:

1. Do not rashly follow those who advocate that we can “just get infected and move on with life”. Get your booster vaccination if you have not already got it.

2. Work to maintain your protection via reliable masks and effective indoor ventilation to reduce your risk of any infection. Avoid risky events, especially crowded, unmasked outdoor events or venues.

3. Reduce your risk of long-term complications by keeping as fit as possible, especially maintaining a good body weight and keeping the mind active.

4. If you have been infected in the past, consider seeing your doctor to screen for cardiac and metabolic disease.

5. Finally, remember that with the limited testing currently, we cannot use case numbers to guide us about a new wave, especially one that may be more severe. Hospital admissions are delayed markers and we will only see a rise two to three weeks after a new wave.

Keep abreast of the science and data as it develops so that we can modify our behaviour according to the best evidence.

Datuk Dr Amar-Singh HSS is a consultant paediatrician. Comments: letters@thesundaily.com