COVID vaccines

1. What can we expect from first generation
Covid-19 Vaccines
Peiris M & Leung GM. Lancet 2020; 396; 1467 - 69
• WHO recommends successful vaccines should show disease risk reduction of
atleast 50% with 95% CI
• Impact on infection & transmission is not being assessed
• Even if vaccine confer protection from disease, it maynot reduce transmission
• Animal Challenge studies have shown  reduction in pathology, viral load
• Reinfection has been reported, but no information on secondary spread
• Pre existing Neutralizing Antibodies afford protection against infection
• Passive antibody transfer protected animals against Covid-19
• Role of mucosal immunity & T cell is not clear

2. Q & A on Covid-19 Vaccines
• Qs.1. How much does a vaccine reduce the risk of Covid-19 & its complications ?
• Ans. Regulatory authorities expect that vaccine for licensure would prevent
disease or decreases its severity in atleast 50% of people who are vaccinated.
• Qs.2. How safe is a vaccine candidate ?
• Ans. Studies should have 15,000 or more people vaccinated and followed up for
time periods sufficient to detect most safety issues (2 months). Mild adverse
events like soreness at injection site, fever, fatigue & myalgia may be unpleasant
but patients accept them if they are mild & resolve quickly.
• Neurological complications maybe of more concern, but have not been found in
any of the vaccines.

3. • Qs. 3. Will the vaccine be effective for all patients ?
• Ans. Patients with severe disease and elderly are usually under represented
in most clinical trials. Trials with children and pregnant women will start
once vaccine is safe in others.
• Qs.4. Can vaccinated people stop worrying about Covid-19 ?
• Ans. While vaccine will help protect individual patients and those around
them. Herd immunity will take months to occur for community transmission
to stop.
• Even after vaccination, SARS CoV 2 will be a continuing public health
concern. Effective measures to decrease transmission, like social distancing,
limiting size of gatherings and wearing mask in public will be needed for
atleast several more months.

4. • Qs.5. What are the benefits of getting a Covid-19 vaccine ?
• Ans. Covid-19 can cause severe medical complications and lead to death , we
have seen young and otherwise healthy, health care workers loose their lives.
Once you get Covid-19, you may spread it to your family, especially elderly
parents, friends and others.
• Getting a Covid-19 vaccine can help protect you by preventing you becoming
seriously ill.
• Qs.6. Can Covid-19 vaccine give you Covid-19 disease ?
• Ans. No. The Covid-19 vaccines currently available donot use live virus that cause
the disease. The vaccine will not cause Covid-19 infection in you.
• But the vaccine will take atleast a few weeks to build up immunity in your body to
protect you, in the mean time, you could pick up infection and so must continue
to take precautions for preventing transmission of infection to you.

5. • Qs.7. What are the possible side effects of Covid-19 Vaccine ?
• Ans. A Covid-19 vaccine can cause mild side effects either after the first or
second dose of intramuscular injection. This includes local pain, redness,
swelling, tenderness or bruising at site of injection. There could be fever, chills,
nausea and muscle or joint pain.
• Usually these symptoms are mild and resolve quickly. Taking Paracetamol tablet
can also decrease the symptoms.
• Some vaccines have caused allergic reactions, but that has been traced to PEG,
a lipid stabilizer, but it is not used in either Covishield or Covaxin.
• Qs.8. Can I get a Covid-19 vaccine if I have a history of allergic reactions ?
• Ans. If you have history of allergic reactions not related to vaccines or injection
medications, you may still get a Covid-19 vaccination. You would be monitored
for 30 minutes as most serious allergic reactions occur within that time span.
• If you have history of severe immediate allergic reaction do inform the doctor,
if it is after the first dose, donot take the second dose.

6. • Qs.9. Can pregnant or breast feeding women get the Covid-19 vaccine ?
• Ans. There is no data on the safety of Covid-19 vaccines in pregnant or
breastfeeding women. But nor is there any reason to suggest that vaccine
shouldnot be taken.
• Qs.10. Should I get the Covid-19 vaccine even if I have already had Covid-19 ?
• Ans. Getting Covid-19 might offer some natural protection or immunity from
reinfection with the virus which causes Covid-19. But it is not clear how long
this protection lasts.
• Because reinfection is possible and Covid-19 can cause severe medical
complications, it is recommended that people who have already had Covid-19
should be vaccinated.

7. • Qs.11. Can I stop taking safety precautions after getting a Covid-19 vaccine ?
• Ans. Experts want to learn more about the protection that a Covid-19 vaccine
provides and how long immunity lasts before changing safety
recommendations.
• Factors such as how many people get vaccinated and how the virus is
spreading in communities will also affect these recommendations.
• In the meantime, it is recommended that after vaccination, you should
continue to avoid close contact and maintain social distancing. Wear mask
when in public, wash hands with soap and water and practice good hygiene.
• Qs.12. Is there anyone who shouldnot get a Covid-19 vaccine ?
• Ans. No vaccine is yet available for children
• Data on its effect on immunocompromised patients is not available.
References:
1. Goodman JL et al. JAMA 2020;oct , E1
2. Mayo Clinic: Covid-19 Vaccines: Get the facts

8. Next Generation Covid-19 Vaccines