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Insights into Editorial: Why are ‘breakthrough’ infections a concern?

 

Context:

India’s second wave has not fully dipped and over the past seven days, daily infections of COVID-19 have logged over 40,000 cases.

The rise in daily infections is primarily seen in Kerala and Maharashtra, which paradoxically are also among the States which have a high rate of vaccination.

In this context, there are concerns about the rise in ‘breakthrough infections’ or confirmed infections in those who have got the second dose of the vaccine at least two weeks earlier.

 

What is ‘breakthrough infection’?

  1. If a person gets infected with the SARS-CoV-2 virus 14 days after the second shot of the vaccine, it is called a ‘breakthrough infection’.
  2. Any infection that occurs either after the first dose or after the second dose of the vaccine is a breakthrough infection. These vaccines that we are using currently are disease-modifying vaccines, not infection-preventing vaccines.
  3. The two-week window is the time it takes for the body to produce necessary antibodies following a shot of the vaccine.
  4. A ‘breakthrough infection’ refers to the virus being able to penetrate the protective barrier of antibodies.
  5. There are no official estimates, nationally, of how many ‘breakthrough infections’ have been reported in India but news reports in mid-August, quoting unnamed officials, estimated that 80,000-100,000 people got infected, nearly half in Kerala.
  6. The State has a COVID-19 genome surveillance programme that periodically monitors the prominent coronavirus variants as well as whether some variants are more closely linked to instances of ‘breakthrough infections’.
  7. With over 66 crore vaccine doses administered since the vaccination drive commenced in January, India has now inoculated at least half its adult population with at least one dose, and 16% with two.
  8. The S. Centers for Disease Control and Prevention reports that the viral load in those with a ‘breakthrough infection’ can be as much as those unvaccinated, which is why mask mandates are back despite significant vaccination coverage.
  9. The ‘breakthrough infections’ occur is not a surprise. In clinical trials, all vaccines available have reported efficacy rates between 70% and 90%.
  10. This implies that between 10% and 30% of a vaccinated population will be vulnerable to infection.
  11. Vaccines, however, were premised on inuring the body to disease and so far the evidence is that they are overwhelmingly effective.
  12. The bigger concern, however, is that those with a ‘breakthrough infection’, under the belief that they are fully protected, may be less stringent with using masks and could be carriers of infection.

 

No surprise if thousands of breakthrough infections:

  1. The role of vaccines is in their “drastic reduction” of hospitalisations, serious disease, and the need for oxygen or ventilators.
  2. There have been many reports of Indians being infected with the SARS-COV2 virus even after they have received the vaccines.
  3. India is currently using three vaccines — the Serum Institute of India’s Covishield, Bharat Biotech’s Covaxin, and the Russian vaccine Sputnik V that is currently available only in the private sector.
  4. Covisheld claims a vaccine efficacy of 82 per cent (two doses administered at 12 weeks interval), Covaxin claims 77.8 per cent efficacy, and Sputnik V over 91 per cent efficacy.
  5. All vaccines were tested for whether they prevent serious disease, hospitalisation, and death.
  6. The ICMR’s stand is in line with that of the Centers for Disease Control. According to the CDC, Vaccine breakthrough cases are expected. Covid-19 vaccines are effective and are a critical tool to bring the pandemic under control.
  7. However, no vaccines are 100 per cent effective at preventing illness in vaccinated people.
  8. There will be a small percentage of fully vaccinated people who still get sick, are hospitalised, or die from COVID-19.

 

Is the Delta variant responsible for the rise in cases?

  1. When the underlying coronavirus variants were analysed in the Kerala study, 126 were found to have the Delta variant (B.1.617.2), nine had the Kappa variant (B.1.617.1) and six had Delta-Plus variants, that is sub-lineages of the Delta with one or more of its defining mutations.
  2. These mutations mostly help the virus escape detection by antibodies. The India SARS-CoV-2 Genome Consortium (INSACOG), which monitors emerging variants nationally, has analysed 51,651 coronavirus genomes.
  3. Delta has also been demonstrated to reduce antibody levels elicited by vaccines. Antibody levels are not the only measure of protection and immunity by T-cells, which cannot be easily evaluated in a lab, are also important for neutralising the virus.
  4. However, vaccine production technologies such as m-RNA and DNA are premised on their ability to be tweaked quickly for newer variants.
  5. The makers of Covaxin claim that their vaccine, being an inactivated whole virus, is geared up to be more effective against variants than other vaccines primarily targeted at the spike protein.
  6. An ICMR study showed a 2% protection against the Delta variant in a double-blind, randomised, multicentre, Phase 3 clinical trial of Covaxin.

 

India’s Vaccination drive:

  1. PM Modi said that the Government has been working hard from over a year to ensure that maximum numbers of Indians are able to get the vaccine in the shortest possible of time.
  2. Government insisting that India is vaccinating people at world record pace& we will continue this with even greater momentum.
  3. India’s National Covid-19 Vaccination Strategy has been built on a systematic and strategic end-to-end approach, proactively building capacity across R&D, Manufacturing and Administration since April 2020.
  4. While pushing for scale and speed, it has simultaneously been anchored in the stability necessary to sustainably execute the World’s Largest Vaccination Drive.
  5. India has been following a dynamic mapping model based on availability of vaccines & coverage of vulnerable priority groups to take decisions of when to open up vaccinations to other age-groups.
  6. Government of India has proactively engaged and coordinated with stakeholders across the spectrum, from research institutes to national and international manufacturers, global regulators etc.
  7. The strength of India’s private sector vaccine manufacturing capability has been strategically empowered through unprecedented decisive steps, from facilitating public-private collaborative research, trials and product development, to targeted public grants and far-reaching governance reforms in India’s regulatory system.
  8. However, the WHO had urged India to increase vigilance in hospitals, clinics, health centres, and at wholesalers, distributors, pharmacies and suppliers of medical products.

 

Conclusion:

While it is a fact of evolution that viruses would mutate to be able to avoid antibodies, and vaccines, therefore, would have to keep being upgraded, it seems that the moment appears to have come too soon.

A country like India, in spite of being a major vaccine producer in the pre-pandemic era, has only now managed to get production lines to deliver one crore vaccines a day.

While other vaccines are in the pipeline, all of them are designed on the Wuhan-virus platform and although companies claim that the strength of m-RNA and DNA-based vaccine platforms lies in the ability to quickly tweak them to accommodate new variants, there are no reports yet, anywhere in the world.

Vaccine makers who may have got emergency-use authorisations but are a while away from launch, should ideally move to making vaccines for the Delta variants and not rely on their existing pipeline.