COVID reinfections, and what it means for vaccine development

FPK Photo/Qayoom Khan.

Showkat Ahmad from Anantnag district of Jammu and Kashmir had first contracted the virus in July this year. After remaining asymptomatic, he had tested negative after only a week.

Later in the month of September, Showkat developed cough and fever. Suspecting it to be a seasonal flu, he started the treatment accordingly.

However, the condition continued to get worse every day. When a CT scan revealed bilateral pneumonia, his family shifted him to SKIMS, Soura, where he got a rapid COVID test which came back positive.

On the 30th day of September he was hospitalised at SKIMS where his treatment started. This time he was severely symptomatic and required oxygen concentrator as his saturation levels continued to dip.

Showkat is one of the two people who got re-infected with the COVID causing Coronavirus in Kashmir.

During hospitalization, he was tested 4 times for COVID and tested positive each time. After months of being discharged from the hospital, Showkat Ahmad, though back home now, has not completely recovered. A classic case of Long COVID, Showkat gasps for breath even after a short walk.

“His condition has not gone back to what we would call normal,” says his son, who was his caregiver at the hospital. “He still requires an oxygen concentrator to keep his oxygen level stable”.

As the world is headed towards vaccine development for COVID, reinfections pose a serious challenge to this process.

So far, two cases of COVID reinfection have been reported in Kashmir, according to Professor Rafi A Jan, who is the head of the COVID management team at Sher-i-Kashmir Institute of Medical Sciences (SKIMS), Soura Srinagar.

“It can be more than that, but only 2 cases are documented well,” says Prof. Rafi, adding “both the patients were symptomatic and sick so we had to admit them here.”

Right now, there are no reinfection cases in the hospital, he adds.

While the global heath system is stretched to its limits fighting the pandemic, the emerging cases of reinfections pose questions about the longevity of the protection provided by antibodies.

As the COVID cases continue to increase worldwide, reports of reinfections are surfacing too.

Earlier this month, reinfections were reported in health care workers in Delhi. Similarly, reinfection were reported from Bangalore and Mumbai too.

While WHO is yet to issue guidelines to define a reinfection, it warned that the global data suggested that the immunity attained by a COVID infection may not be lifelong and that, though rare, reinfections were a possibility. Maria Van Kerkhove, head of the WHO’s emerging diseases and zoonosis unit, has said that researchers are still trying to determine how long an antibody response lasts after someone is infected with the virus.

What is a reinfection?

When an individual is cured off the infection for the first time, but tests positive again after some time, they are said to be reinfected. COVID is caused by the SARS CoV2, strain of the Coronaviridae family of viruses. Other members of this family of viruses are known to reinfect previously recovered individuals.

The genomic study of the virus’s genetic material, RNA in case of SARS CoV 2, can illuminate a number of things. It can differentiate between a reinfection and a reactivation.

If the genetic material of the viral samples from the two infections is different, it indicates that the individual was infected by two different strains each time.

On the other hand, if the genetic material of the viral samples is the same, it points towards the reactivation of the first viral particle which was still present inside the host but in an inactive state.

There is a third possibility as well, that the virus evolved into a different strain inside the host itself.

Among the first global cases of COVID reinfection was a 33 years old man from Hong Kong. He had tested positive again after 3 and a half months from the first infection. In this case, the genetic sequencing of the viral samples from both the infections had revealed that the two strains were different from each other.

As a matter of fact, the second strain was closely related to strains found in Europe at that time, where the person had a travelled to before testing positive for the second time.

What do reinfections mean for Herd Immunity and Vaccine development?

Herd immunity, sometimes also called population immunity, is an indirect protection from an infectious disease. It is achieved when a significant proportion of a population becomes immune to the infection, either through vaccination or by prior infection.

So, when an individual becomes immune to the infection, not only does it protect them from the disease but it also stops the chain of transmission, hence providing indirect protection to the other members of the community.

Like other infectious diseases, reinfection with COVID also has implications on both, Herd Immunity and Vaccine development. If members of the population keep getting reinfected, it means that the immunity acquired from the first exposure is not long lasting and hence the chain of transmission will not be effectively stopped.

Reinfections indicate mutations in the virus, which are a significant detail for vaccine development. Although reinfections do not rule out the importance of a vaccine for stopping the transmission of infection, they however, complicate the process.

Each time a virus replicates, there are very high chances of it acquiring changes in its genetic material.

Over repeated cycles of replication, these mutations accumulate, which means that at the same time there are a number of mutated variants of the virus in circulation in different regions of the world. This necessitates the development of different types of vaccines for each type of variant.

Moreover, as new variants take over the older ones, there might be a need for seasonal vaccine shots. Specific variant and mutation studies will be required to develop such regional and seasonal shots.

According to Prof. Rafi, right now the cases of COVID reinfection globally are sporadic and clusters of reinfections have not been reported.

More research about the nature of the infection and the immunity acquired is essential to understand reinfections better. Surveillance holds immense importance in keeping a track of reinfections. This in turn is needed to determine the frequency of reinfection.

As far as surveillance at primary health care level in Kashmir is concerned, there is no active surveillance in place right now.

Recently, Britain began mass vaccinating its population. Whether or not the vaccine provides long lasting immunity remains to be seen, at the same time extensive research on reinfections is urgently required as it will determine the type of vaccines that need to be further developed.


Misbah Haqani is an independent researcher interested in understanding the social determinants of health and the socio-political aspects surrounding healthcare in Kashmir. 

Click to comment
To Top