What is this vaccine against covid-19?

By Dr. Kavindya Marapana

COVID-19 has impacted millions of lives worldwide. Sri Lanka reported its first case of COVID-19 on 27thJanuary 2020 and since then the epidemic has affected Sri Lanka significantly, especially since the second wave of COVID-19 in October 2020, causing a severe health, economic and social burden. Globally, whilst many people may have asymptomatic infection, around 40% of the infected persons develop a range of mild symptoms which include fever, a new and continuous cough, shortness of breath, sore throat, fatigue, loss of appetite, diarrhoea, etc. Only around 15% of the patients develop severe complications such as pneumonia, and out them around 5% suffer from life-threatening diseases including severe respiratory distress syndrome, thromboembolic events and multi-organ failure. In Sri Lanka, 79, 999 cases have been identified to the date of writing and although the incidence of COVID-19 related complications seem to be low, 445 deaths have been reported up-to-date, including paediatric deaths. COVID -19 is also believed to have long-term effects on neurological system which is still in research stage.

The Ministry of Health has introduced a Covid-19 vaccine, which is considered safe and efficacious as evident from the available information about vaccine trials. Given the high priority requirement of safeguarding essential healthcare facilities of the country, adhering to global Covid-19 vaccination prioritization guidelines and recommendations by the National Advisory Committee of Communicable Diseases, healthcare staff and other support frontline workers have been inoculated.

Over 280 different COVID-19 vaccines are at various stages of development. Some have been made with the help of currently available vaccine technology, and completely new approaches have been adopted in producing others. While it normally takes several years to develop a vaccine, scientists across the world have worked collaboratively and expeditiously to achieve the same amount of work in a few months to make a safe and effective vaccine available as soon as possible. Although clinical trials have been carried out more rapidly than they have for other vaccines, this has been achieved by conducting some of the steps in parallel rather than sequentially and vaccine safety has not been compromised.

With the initiation of the vaccination programme in Sri Lanka, lot of questions have been raised by the public and we believe to answer a few common questions that have been raised frequently with the expertise of Dr. Chintha Karunasekara, Consultant Microbiologist at Lady Ridgeway Hospital for Children.

What is the vaccine given to
the Sri Lankans at the moment?

It is the COVISHIELD vaccine made by the Serum Institute of India (SII) that is brought down to Sri Lanka as the first batch of vaccines against corona virus. It is the same vaccine as the COVID-19 Vaccine AstraZeneca (ChAdOx1nCoV-19 Corona Virus Vaccine-Recombinant) developed by the University of Oxford but is developed to be effective at the temperatures of South Asian countries.

How does it protect me against COVID-19?

It is a viral vector vaccine, which uses a safe, weakened virus (adenovirus) which does not have the ability to multiply inside the body. It is genetically engineered to include a protein of SARS-C0V-2 (SARS-Cov-2 spike S) which triggers an immune response in the body against the COVID-19 virus, which protects the body from the possibility of developing disease or severe disease leading to death. The virus in the vaccine is destroyed after introducing the protein in the body. After the first dose of vaccine, the second dose is recommended to be taken in four weeks time. But the latest studies are recommending to increase the gap between the two doses up to 12 weeks for increased efficacy. The duration of protection by the vaccine is still not confirmed and is currently being studied. Therefore, with the current data it may require for it to be repeated yearly.

Is it safe for me to take it?

The COVID-19 vaccine AstraZeneca is currently under phase 3 vaccine trials and is found to be the most safe and efficacious vaccine among the vaccines currently being used. But there are instances where the vaccination should be strictly avoided and informed to the vaccination team without hesitance;

Known allergic reactions to the constituents of the COVISHIELD vaccine (L-Histidine, L-Histidine hydrochloride monohydrate, Magnesium chloride hexahydrate, Polysorbate 80, Ethanol, Sucrose, Sodium chloride, Disodium edetatedihydrate (EDTA), Water for injection)

History of severe allergic reactions leading to hospital admission or anaphylaxis.

Pregnancy , lactation and in children less than 18 years (not enough evidence is still available for the safe use of the vaccine among these groups)

Special precautions are to be taken if you are having a disease affecting bleeding and coagulation.

There are special situations where the vaccination is to be postponed for 4 to 8 weeks, and those are;

If you have any symptoms suggestive of COVID-19.

If you are suffering from an acute illness and not fit for the vaccination.

If you are already diagnosed with COVID-19 and received anti-CoV 2 monoclonal antibodies or convalescent plasma as a treatment option.

Being under regular treatment for long term diseases is not a reason to avoid the vaccine. But those conditions must be communicated to the doctor prior to the vaccination.

Why should I take it? Can I still be protected against COVID-19 without the vaccine?

Vaccination is one of the powerful public health interventions to combat this pandemic. Two key reasons to take the vaccine are to protect ourselves and to protect those around us. After vaccination most are protected from disease and severe disease. Vaccination curbs the spread of the virus by reducing the number of infections in a population.

The more people are immunized, the better the chances of reaching herd immunity. Herd immunity is even unvaccinated people in a population can be protected from a certain virus, like COVID-19, if a certain threshold of vaccination is reached in that population. Likewise, vaccines protect individuals, also protect communities.

Does it protect me for lifetime?

Once an individual is vaccinated, how long will their immunity to Covid-19 last? To answer this question more data from vaccine trials have been collecting and it depends on how a vaccine performs and how SARS-CoV-2 acts in the real world. For more longer immunity may need a booster vaccine.

Can I still transmit the disease to
those who are around me?

Vaccines are typically designed to prevent people from getting sick with the virus, but it is not yet clear if the COVID-19 vaccines can stop you from transmitting the virus to others. This is why is it important for people to continue taking precautions such as physical distancing, hand washing, wearing masks and avoiding gatherings, especially in poorly-ventilated spaces

But the most recent studies have shown the COVID-19 AstraZeneca vaccine to reduce the risk of transmission by 67%, which is a ray of hope that in the near future further developments would take place to further reduce the transmission.

The more people are immunized, the better the chances of reaching herd immunity.Herd immunity is when a population can be protected from a certain virus, like COVID-19, if a threshold of vaccination is reached

How bad can the side-effects be?

Around 75% of the healthcare personnel who received the vaccine reported to have mild to moderate symptoms as a result of the ongoing immune reaction following the vaccination. The most commonly reported symptoms were fever (low to high grade), chills, rigorus, muscle and joint pains, fatigue, lethargy, loss of appetite and vaccine site pain and swelling.

Less commonly abdominal pain, minor allergic reactions, enlarged lymph nodes have been reported but severe allergic reactions, anaphylaxis have not been reported so far in Sri Lanka.

The vaccination programme which is started by the government with the frontline healthcare workers is now started in stages to reach the rest of the population in Sri Lanka and the type of vaccine could be different to COVISHIELD, which we hope to write about in the future.