Dr. Sushmita Ganguli

Abstract:

Background: The Coronavirus 2019 disease has created a havoc in the world and vaccines are required to create quick herd immunity to stop the mutations and prevent the emergence of new variants. Through this literature review we aim to evaluate the efficacy and safety of vaccines in the real- world scenario. 

Methods: We searched databases of PubMed, Embase, Wiley from December 2020 to April 2022. Studies that examined the effectiveness of Covid 19 vaccines among the fully and partially vaccinated individuals were included. 

Results: A total of 58 studies were included from published articles in journals. A single dose of vaccine was 41% effective in preventing SARS COV 2 infections, 52% for symptomatic Covid infections, 66% for hospitalisations, 45% for intensive care unit admissions and 53% for Covid 19 related deaths. Two doses were 85% effective in preventing SARS COV 2 infections, 97% for symptomatic Covid 19 infections, 93% for hospitalisations, 96% for intensive care unit admissions, 95% for covid 19 related deaths (4) (Qiao Liu, 2021 Nov 14).

Conclusion: The efficacy and safety of Covid 19 vaccines is reassuring. It significantly reduces severe cases and fatality due to Covid 19. It is highly effective in preventing covid 19 symptomatic cases and infections. With the constant emergence of new variants due to mutations, the vaccine administration at quick pace is the available and feasible solution till date. The vaccine hesitancy and vaccine inequity need to be addressed to improve vaccination coverage globally to fight this pandemic. 

Keywords: SARS COV 2, Covid 19, Vaccine safety, Vaccine effectiveness, Real world, Literature review, Covid 19 vaccines

Introduction:

Covid 19 is an infectious disease caused by SARS COV 2 virus. Most people infected with the virus experience mild to moderate symptoms but some become severely ill and require medical attention. People of any age can get affected with the disease and the disease can be fatal. The most common symptoms are fever, cough, tiredness, loss of smell or taste. The less common symptoms are sore throat, headache, aches, diarrhoea, skin rashes. The serious symptoms are shortness of breath, breathing difficulty, loss of speech, confusion, chest pain. Immediate medical attention is required for serious symptoms whereas people with mild to moderate symptoms usually recover without hospitalisation. 

According to WHO statistics, there have been more than 529,410,287 confirmed cases of Covid 19 reported globally till 6th of June 2022 and more than 62,96,771 global deaths have been recorded. More than 11,94,76,44522 crore people have been administered vaccines against covid 19 till 31^st May 2022. The impact of vaccines on the pandemic is highly dependent upon the approval of vaccines, the effectiveness of the vaccines, the vaccine manufacturing, the vaccination coverage and the development of new variants. The vaccines are an important tool to stop the pandemic along with surveillance, contact tracing, isolation and preventive measures. The first vaccine to get approval for emergency use was Pfizer.

Vaccines are assessed to ensure they meet the standards of quality, safety, efficacy and the benefits against any potential risks. Individual countries also have the authority to provide emergency approval for the vaccines. Several types of vaccines are developed including:

1. Inactivated virus vaccines: virus is inactivated or weakened to generate the immune response 
2. Protein based vaccines: harmless fragments of protein are generated to trigger immune response by mimicking covid 19
3. Viral vector vaccines: uses safe virus to work as a platform to generate covid 19 proteins to trigger immune response
4. RNA and DNA vaccines: uses genetically engineered RNA or DNA to generate a protein that safely prompts an immune response

WHO advises to take all recommended vaccine doses as soon as the turn comes, including the booster dose, even after contracting covid-19. It is still possible to get Covid even after getting vaccinated, hence preventive measures need to be followed. The available covid vaccines are safe for people who are 18 years and above including those with pre-existing conditions and autoimmune disorders. Vaccines can be safely taken during pregnancy and while breastfeeding. Children too can be safely vaccinated against covid 19. Immunocompromised persons should be prioritised for vaccine dose after two to three months of first dose. However, it recommends that people with history of allergic reaction/ anaphylaxis to covid 19 vaccine ingredients to not get vaccinated. If someone has fever above 38.5 degrees Celsius on the day of vaccination, it should be postponed until recovery. One should complete the isolation period if contracted with covid 19 before getting vaccinated. 

Thus, fair access to covid 19 vaccines is needed to drive the vaccination at full pace globally to contain the pandemic. The benefits of vaccines outweigh the risks and countries need to address the vaccine hesitancy issue to support the vaccination drive. The real- world case studies have shown remarkable efficacy and safety of the covid vaccines and people who have still not been vaccinated should be encouraged to take their prescribed doses. 

Main Body:

As stated by WHO, until May 2022, 57 countries have vaccinated 70% of their population, which are almost high- income countries. Even though it is a huge logistic and scientific achievement, almost 1 billion people in lower income countries still remain unvaccinated. 

Side effects and Adverse events of vaccines:

Mild to moderate side effects after vaccination is reported by certain individuals which includes fever, headache, tiredness, muscle ache, chills, pain and redness at the site of injection. Most side effects go away within few days on its own. The side effects can be managed by increased fluid intake, adequate rest and painkillers for symptomatic relief. In case the pain at site of injection does not subside in 1 day, it is advised to contact the nearest healthcare provider. Serious adverse effects are usually rare but possible which include difficulty in breathing, chest pain, confusion, loss of speech or mobility after vaccination. The WHO keeps on monitoring the vaccine to detect and respond to the adverse events. 

A published review conducted to study the effectiveness of covid vaccines showed that the vaccine efficacy was 85% for prevention of Alpha variant, 75% for Beta variant, 54% for Gamma variant and 74% for Delt variant. 1.5% reported for adverse events, 0.4% for severe adverse events and 0.1% for death after vaccination (1) (Qiao Liu, 14 November 2021). Another review showed that the effectiveness of Pfizer vaccine was 91.2%, Moderna was 98.1% and CoronaVac was 65.7% (2 (Caifang Zheng, 2022 Jan)). Another review aimed to study the vaccine effectiveness against delta variant showed 88% effectiveness for Pfizer and 67% effectiveness for AstraZeneca vaccines (3) (Chang-Jie Cheng 1 2, 2021 Dec 16;).  

Myths and Facts with vaccine:

1. Myth: Dangerous ingredients are there in vaccines

Fact: Ingredients like preservatives, tissues, antibiotics, food proteins, latex, metals are not             present in the vaccines.

2. Myth: The natural immunity developed by getting sick with covid 19 is better than the immunity from covid 19 vaccine

Fact: Vaccination is much safer and dependable way to develop immunity against covid 19

3. Myth: Covid 19 vaccines cause new variants

Fact: Vaccines do not create new variants, instead it helps in controlling emergence of new variants

4. Myth: All events reported to the Vaccine Adverse Event Reporting System (VAERS) are caused by vaccination

Fact: Anyone can report adverse to the VAERS irrespective of the causation. Hence VAERS data alone cannot suggest the covid 19 vaccination to be the sole reason. 

5. Myth: mRNA vaccine is not considered a vaccine

Fact: m RNA vaccines work differently and trigger an immune response.

6. Myth: Covid 19 vaccines can alter DNA 

Fact: Covid 19 vaccines do not change or alter DNA in any way.

7. Myth: Covid 19 vaccine can make you sick with Covid 19

Fact: Covid 19 vaccines do not contain live virus and hence cannot cause covid 19

The following vaccines have been given Emergency Use Listing (EUL) by the WHO. 

SR No	Name of Vaccine	Composition	Year Of Approval
1	Pfizer/ BioNtech Comirnaty Vaccine	Messenger RNA	31 December 2020
2	SII/ Covishield and AstraZeneca /AZD 1222	Vector vaccine	16 February 2021
3	Janssen/ AD26.COV 2.S vaccine by Johnson and Johnson	Vector vaccine	12 March 2021
4	Moderna Covid 19 vaccine mRNA 1273	Messenger RNA	30 April 2021
5	Sinopharm Covid 19 vaccine	Inactivated virus	7 May 2021
6	Sinovac-CoronaVac vaccine	Inactivated virus	1 June 2021
7	Bharat Biotech BBV152 Covaxin Vaccine	Inactivated virus	3 November 2021
8	Covovax (NVX-CoV2373) vaccine	Protein based	17 December 2021
9	Nuvaxovid (NVX-CoV2373) vaccine	Protein based	20 December 2021

Conclusion:

Globally, an effort should be made to convert vaccines into vaccination. Countries must ensure fair and equitable access to vaccines and roll them out to protect their people and reach at least 70% of coverage as fast as possible, including 100% of 60 years and above, 100 % of healthcare workers and 100% of those with underlying conditions. The gaps of operational, financial and vaccine hesitancy due to misinformation and disinformation should be quickly filled up. This narrative review shows high effectiveness of Covid vaccines against SARS CoV 2 infection in real-world settings. However scarce data on the new variants and shortness of study time may limit the conclusions. Overall, accelerating the vaccine coverage globally and solving the vaccine inequity is the most urgent matter in the fight against the covid 19 pandemic.

References:

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[2]. Zheng C, Shao W, Chen X, Zhang B, Wang G, Zhang W. Real-world effectiveness of COVID-19 vaccines: a literature review and meta-analysis. International Journal of Infectious Diseases. 2022 Jan 1;114:252-60.

[3]. Henry DA, Jones MA, Stehlik P, Glasziou PP. Effectiveness of COVID‐19 vaccines: findings from real world studies. The Medical Journal of Australia. 2021 Aug;215(4):149.

[4]. Golob JL, Lugogo N, Lauring AS, Lok AS. SARS-CoV-2 vaccines: a triumph of science and collaboration. JCI insight. 2021 May 5;6(9).

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