Focus/Spotlight

A new hope for the world: Covid-19 vaccine 

By Dr. Charuni Kohombange  

 

Amidst a global pandemic, it was with much anticipation that the introduction of the Covid-19 vaccination took place. While many affluent countries have initiated vaccination programmes, Sri Lanka launched the Covid-19 vaccination drive on 29 January, administering the Covishield vaccine donated by India under the Vaccine Friendship (Maithri) initiative. At the time of writing, nearly 100,000 healthcare workers were being vaccinated across the country.  

Vaccinations were initiated at the Colombo National Hospital, Colombo North and Colombo South Teaching Hospitals, Mulleriyawa Base Hospital, Homagama Base Hospital, and the National Institute of Infectious Diseases. The programme is extended to vaccinate all healthcare workers islandwide during the subsequent days. 

Nevertheless, the public is feeling much hesitance and doubt about the safety and effectiveness of the vaccine. The aim of this article is to clarify these common doubts about the Covid-19 vaccine.  

 

What is a vaccine? 

 

A vaccination is a simple, safe, and effective way of protecting people against harmful diseases. It uses the immune system (natural defence mechanism) of the body to build resistance to specific infections and to strengthen the immune system to fight against invading pathogens.   

 

The Covid-19 vaccines that have been developed to date

Types of vaccines for Covid-19

 

According to the World Health Organisation (WHO), more than 50 vaccine trials are currently being carried out around the world. There are about six vaccines which have been found to be safe and effective via large-scale studies and approved for emergency use by the Food and Drug Administration (FDA) of the US and local authorities.  

There are three main approaches in manufacturing a vaccine. The differences lie in whether they use a whole virus, just parts of the virus that trigger the immune system, or just the genetic material that provides the instructions for making specific proteins. Similarly, vaccines against Covid-19 are also manufactured with these three approaches.  

 

Manufacturing the AstraZeneca vaccine

 

The AstraZeneca vaccine is a viral vector vaccine. In manufacturing this vaccine, the gene (part of DNA of the coronavirus spike protein) has been combined with a harmless virus. The Oxford-AstraZeneca team used a modified version of a chimpanzee adenovirus as the viral vector to deliver genetic materials into cells.  

In general, DNA is not as fragile as RNA, and the adenovirus’s tough protein coat shields genetic material inside. Hence, the Oxford-AstraZeneca vaccine for Covid-19 is more stable than the mRNA vaccines. Therefore, the Oxford vaccine does not need to be stored in freezing temperatures, and the vaccine is stable at refrigerator temperatures at 38-46°F (2-8°C). 

 

How does it work?

 

When the vaccine is injected, it triggers a complex bimolecular process to produce molecular proteins. The immune system is trained to identify the antigen and mounts a response by producing antibodies and cell-mediated immunity against the spike proteins to destroy the pathogen. 

 

Clarify your doubts about the AstraZeneca-Oxford vaccine 

 

Sri Lanka Medical Association (SLMA) Immediate Past President and Asia Pacific Academic Consortium for Public Health (APACPH) Vice President (VP) Prof. Indika Karunathilake, who is an active member of the Covid-19 technical committee, clarified the following common doubts about the Covid-19 vaccine: 

 

With the prevailing pandemic, researchers rushed to develop a vaccine. Is the safety and efficacy of the vaccine reliable? 

Researchers have never skipped any step in the usual development of vaccines. However, the process was made faster, as it was promptly funded and the genetic data of the virus was readily available with the scientists. Many companies and research institutes co-ordinated to manufacture vaccines, sharing a common goal.  

 

Does the vaccine grant an Emergency Use Authorisation (EUA)? 

An EUA is a mechanism to facilitate the timely availability of medical products including vaccines, especially during public health emergencies such as the current Covid-19 pandemic. In this type of emergency situation, authorities such as the FDA use the available evidence and carefully analyse the potential benefits over risks and issue an EUA if the benefits clearly outweigh the risks.  

On 30 December 2020, the UK authorised the emergency use of the AstraZeneca-Oxford vaccine for individuals who were 18 years or older. This vaccine was developed at Oxford University with AstraZeneca collaboration. People in the UK started receiving the vaccine from 4 January 2021. Since then, many countries have granted EUA of the vaccine. On 6 January, the AstraZeneca-Oxford vaccine officially announced that Serum Institute of India has obtained EUA to reproduce and distribute the vaccine. 

Serum Institute of India is a leading vaccine manufacturer and has been the main vaccine supplier for Sri Lanka’s successful national immunisation programme.  

The National Medicinal Regulatory Authority of Sri Lanka (NMRA) has also approved EUA for the AstraZeneca vaccine. The vaccine manufactured by the Serum Institute of India is named “Covishield”, and is a rebranding of the AstraZeneca vaccine manufactured in the UK.    

 

Three scenarios depicting the effects of administering the vaccine to the population

Are there differences in the efficacy levels of the Covid-19 vaccine? Does the AstraZeneca-Oxford vaccine show satisfactory efficacy? 

Efficacy levels of different vaccines were determined by different settings with different criteria to determine study populations. Therefore, it is not meaningful to compare efficacy levels between different vaccines. Furthermore, there are many other factors such as safety, logistics, and feasibility when selecting a vaccine.  

According to the available data, the combined average across different dosing regimes has found that the AstraZeneca vaccine was 70% effective in protecting against symptomatic disease.  

 

How can we ensure equitable distribution of the vaccine worldwide?  

It is important to remember that unless the majority of the individuals are immunised, we cannot assure effective controlling of the disease by the vaccination.  

This is called herd immunity, i.e., when the majority (over 80%) are immune, everyone is protected.   

Therefore, regardless of financial status, all countries should receive the vaccine equitably. Only if used correctly and equitably can we eradicate the acute phase of the pandemic and allow the rebuilding of our societies and economies. 

Similarly, since resources remain scarce, immunisation programmes will have to prioritise certain groups over others before progressively expanding distribution to all population groups.  

The Covid-19 Vaccines Global Access (COVAX) Facility is a partnership established by the WHO in collaboration with the ACT-Accelerator vaccine partners, the Coalition for Epidemic Preparedness Innovations (CEPI); and Gavi, the Vaccine Alliance.  

COVAX is bringing nations together, regardless of their income level, to ensure the procurement and equitable distribution of Covid-19 vaccines.  

 

What is the process of obtaining the vaccine in Sri Lanka? Is it available in both the state and private sector? 

In order to ensure the equitable distribution of the vaccine, the Ministry of Health has taken the sole authority to distribute the vaccine via the government sector. Since Sri Lanka has a strong public health system and a well-established vaccination programme, this process will be the most reliable method.  

 

What are the common side effects of the Covid-19 vaccine? 

Like all medicines, this vaccine can cause side effects, although not everybody gets them. According to the available data in the UK, following are the possible side effects: 

Very common (may affect more than 1 in 10 people) 

  •         Tenderness, pain, warmth, redness, itching, swelling, or bruising where the injection is given 
  •         Generally feeling unwell 
  •         Feeling tired (fatigue) 
  •         Chills or feeling feverish 
  •         Headache 
  •         Nausea 
  •         Joint pain or muscle ache 

  

Common (may affect up to 1 in 10 people) 

  •         A lump at the injection site 
  •         Fever 
  •         Vomiting 
  •         Flu-like symptoms such as high temperature, sore throat, runny nose, cough, and chills 

  

Uncommon (may affect up to 1 in 100 people) 

  •         Feeling dizzy 
  •         Decreased appetite 
  •         Abdominal pain 
  •         Enlarged lymph nodes 
  •         Excessive sweating, itchy skin, or rash (severe allergic reaction can occur extremely rarely) 

 

During vaccine rollout in Sri Lanka, so far, no serious adverse effects have been reported, even though there were several reports of high fever, headache, and myalgia (body pain).    

 

What are the eligibility criteria for vaccination and what is the frequency of vaccination? 

The vaccine is not recommended if you have ever had a severe allergic reaction needing hospitalisation.

No data is currently available on the use of the Covid-19 AstraZeneca vaccine on children and adolescents younger than 18 years of age. 

Since there is only limited data on the use of the Covid-19 AstraZeneca vaccine in pregnant or breastfeeding women, these categories are also excluded from vaccination.  

If someone is having fever and is not well on the date scheduled for vaccination, it will be postponed to another date.  

If you are undergoing any of the following conditions, inform the doctor at the vaccination visit;  

  • If you have ever had a severe allergic reaction (anaphylaxis) after any other vaccine injection 
  • If you currently have an infection with a high temperature (over 38°C) 
  • If you have a problem with bleeding or bruising, or if you are taking a blood-thinning medicine (anticoagulants like aspirin) 
  • Any other medicines you are taking 

  

How is the vaccine given? 

The Covid-19 AstraZeneca vaccine is injected into a muscle (usually in the upper arm). You will receive two injections and the second injection is given four weeks after the first dose. You will be told when you need to return for your second dose and it is necessary to keep the vaccination card with you.  

 

After completing the vaccination, is it possible to go back to a normal lifestyle? 

Vaccination is an essential preventive strategy, but it is not a replacement for other preventive measures such as wearing a mask, hand hygiene, maintaining social distancing, and avoiding crowded places. All these measures will be effective when in synergy. If we are to gain the maximum benefit of vaccination, adaptation to the new normal is essential. Although it has shown an effective immune response, how long this immunity lasts is not yet confirmed.  

Furthermore, even though the vaccine is effective in reducing severe disease and mortality, so far, there is no research data to prove that it can effectively reduce asymptomatic transmission. To put it simply, vaccines may not stop the coronavirus from entering your body and colonising the nasal cavity. Therefore, it may be possible that people vaccinated for Covid-19 can still carry and transmit the virus, even when they themselves do not have symptoms. 

So, the take-home messages are, have trust in the vaccines recommended by the experts; take it when it is made available; have realistic expectations; and finally, do not deviate from basic preventive measures.