Context: India’s COVID-19 control plan of actions can be the basis for building a much-needed public health infrastructure.
How can vaccine help in eradicating a disease?
- Preventive medicines: Vaccines play a major role in human mastery over infectious diseases by inducing immunity in individuals.
- Herd immunity: When a vaccine is rolled out as a national programme and increasing proportions of people are vaccinated, ‘herd immunity’ level increases and disease frequency decreases in the vaccinated population.
- The ‘herd effect’ of vaccination: That decelerates transmission of the microbe in the whole community, resulting in decreasing disease frequency even in the unvaccinated segment of population.
- Herd immunity plus herd effect reduces the overall disease burden in the community.
- Control: In epidemiology, the common word ‘control’ has a specific meaning: ‘deliberate reduction of disease frequency to a desired level, validated with evidence’.
- For evidence, disease frequencies must be documented both at baseline and on an ongoing basis, through systematic surveillance. So, control interventions include vaccination programme and disease surveillance.
- Elimination: The extreme form of control is ‘elimination’ of transmission of the microbe in a whole country.
- For example, measles and rubella have been eliminated in Sri Lanka through sustained vaccination achieving high coverage.
- Diseases eradicated using vaccine: Eradication is global elimination of an infectious disease. So far, smallpox and cattle plague have been eradicated using their respective vaccines.
- Severe Acute Respiratory Syndrome (SARS) was eradicated in 2003 without a vaccine, using ‘non-pharmacological interventions’, or NPI, systematic case detection, contact tracing and quarantine.
What are the statuses of vaccine candidates in India?
- Protective efficacies: Three COVID-19 vaccines have claims of about 90-95% protective efficacy are BNT162b2 (Pfizer-BioNTech), mRNA-1273 (Moderna) and Sputnik-V (Gamaleya Institute).
- Trial phases: Sputnik-V is under phase 2-phase 3 vaccine trials in India, by Dr. Reddy’s Laboratories. Another vaccine, ChAdOx1 nCoV-19 (OxfordAstraZeneca), manufactured under licence by Serum Institute of India as Covishield, is undergoing phase 2-phase 3 trials in India.
- An indigenous vaccine candidate, Covaxin (Bharat Biotech), found safe and immunogenic in phase 1 and phase 2 trials, is now under phase 3 trial.
- Policy development: In India’s national Universal Immunisation Programme (UIP), vaccines are procured and supplied by the Union government and vaccination is implemented by State governments.
- States have the freedom to surpass policy limits if no fund is sought.
- For example, Delhi used the Measles Mumps-Rubella vaccine when the central government policy was only for Measles vaccine and Sikkim unilaterally used human papillomavirus vaccine to prevent cervical cancer in women.
What can be done to tackle the issues?
- Policy issue: An important policy issue is whether vaccination should be confined to only uninfected individuals or should it be for all people. All test results of infected subjects are available on a computer data base and that is one way to identify those who were already infected.
- Trained staff: The vaccination stations should be staffed with trained personnel and supervised by medical doctors.
- Infrastructure: The site must have a waiting area and a post-vaccination staying area to manage any untoward reaction during the first hour.
- Digital list: A computerised master list with details and mobile numbers of all vaccinated subjects needs to be maintained for the purpose of post-vaccination follow up to document rare side-effects.
- Data management: Data management has to be meticulously planned and executed.
- This is a huge opportunity to eliminate the novel coronavirus from India, setting an example to the rest of the world. With will and wisdom we can, and should, accomplish this.