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Covid-19 vaccine tracker, Aug 28: Why the possibility of re-infection doesn’t render shots useless

Coronavirus (COVID-19) vaccine tracker August 28 Update: The fear is that since the immunity developed by a natural infection does not prevent a re-infection, so would not the immunity triggered by the vaccine.

By: Explained Desk | Pune | August 28, 2020 10:10:38 am
coronavirus vaccine, covid 19 vaccine update, coronavirus reinfection, coronavirus immunity, coronavirus vaccine, moderna vaccine, covid 19 vaccine indiaA lab technician uses a multichannel pipette dropper during the immune response analysis process of the coronavirus vaccine research at the Valneva SA laboratories in Vienna, Austria, on Thursday, August 6, 2020. (Bloomberg Photo: Akos Stiller)

Coronavirus (COVID-19) Vaccine Tracker: Now that it has been confirmed that people can indeed be re-infected with novel Coronavirus after having recovered from the disease once, there have been some concerns about the effectiveness of vaccines being developed for the disease. A vaccine shot is similar to an infection, without making the person sick with the disease.

It is supposed to trigger an immune response in the body just like a natural infection would do. So, the fear is that since the immunity developed by a natural infection does not prevent a re-infection, so would not the immunity triggered by the vaccine. Read in Malayalam

But the strength and longevity of immune response against novel Coronavirus has been an open question throughout. These have not arisen after the first case of re-infection was confirmed in Hong Kong earlier this week.

In the case of natural infection, it has been noticed that the strength of immune response generally correlates with the severity of the symptoms the patient had shown.

People with more severe symptoms usually have shown a stronger immune response, but not necessarily for a longer period.

As of now, it is not known how long the immune response generated by vaccines would last. The human trials of the vaccines are still going on, and this question can be satisfactorily answered only after monitoring the vaccinated volunteers for a long period of time. The researchers who detected the re-infection case in Hong Kong have said that vaccines may not offer life-long protection against novel Coronavirus, and would probably need to be repeated. This is not unusual. Vaccines for several other diseases also need to be repeated after periodic intervals because they do not offer permanent protection.

But the researchers do make an important recommendation. They say the instance of re-infection makes a case for including recovered Coronavirus patients in the vaccine trials.

Also in Explained | What is vaccine nationalism? Why are countries hoarding vaccines?

The re-infection case has also raised doubts whether the vaccines would be successful against all the variants of the novel Coronavirus. The person who has been found to be re-infected was carrying a different variant of the virus the second time.

Shahid Jameel, a virologist, says this is not a concern right now, since most of the vaccines being developed are supposed to be equally effective against all the variants. For blocking the virus, they are targeting regions that are common to all the variants.

“Of course, once these vaccines are in use, it is possible that the virus is forced to mutate in new ways because of pressures of natural selection. In that case, the virus many change in a form that these vaccines are unable to block. But that is in future. As of now, this is not a concern,” he says.

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India in talks to access vaccine being developed by Pfizer

India has begun discussions with pharmaceutical major Pfizer for manufacture and supply of the vaccine it is developing in collaboration with its German partner BioNTech.

Pfizer has recently released data from phase-1 trials, and said it was on track to seek regulatory review for the vaccine as early as October. So far, the company has identified five facilities across the world, including in the United States and Germany, to manufacture the vaccine. It has said it hopes to manufacture up to 100 million doses of the vaccine by the end of the year, and potentially more than 1.2 billion by next year.

Indian companies are among the biggest manufactures of vaccine, but as of now there is no agreement to produce the Pfizer vaccine in India. As of now, Indian companies have entered into agreements to produce vaccines being developed by Oxford University, US biotechnology company Novavax, Johnson & Johnson, and another one being readied at Houston-based Baylor College of Medicine.

Hunt for Coronavirus vaccine: The story so far

  • More than 170 vaccine candidates in pre-clinical or clinical trials
  • 31 of them in clinical trials
  • Six in final stages, phase-III of human trials
  • At least eight candidate vaccines being developed in India. Two of these have entered phase -II trials after completing phase-I.

(As on August 25; source: WHO Coronavirus vaccine landscape of August 25, 2020)

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