Recommendations on a 3rd Dose of the Covid-19 Vaccine: Why Should It Be Given?

Turkey became the first country in the world to begin administering a 3rd dose of the Covid-19 vaccine to its citizens as part of a national health policy. This is a very promising and important development. As of 1 July 2021, everyone over 50 and healthcare workers will have access to a 3rd vaccine dose. This development has raised many questions. In this article, you will find answers to questions about a third Covid-19 vaccine dose.

Since 2019, the world has rapidly come under the influence of the novel coronavirus (SARS-CoV-2) and the Covid-19 disease it causes. We experienced difficult times because of a lack of knowledge about treatment and prevention. Alongside research into the damage Covid-19 causes in the body and how to treat it, vaccine studies were launched to prevent its spread. We finally gained access to vaccine options that had received approval and were being administered.

Vaccination in Turkey continues at full speed. Almost 35 million people have received a first dose, and more than 15 million have received a second. However, the effectiveness of current vaccines against a constantly mutating coronavirus continues to raise questions. In a new statement, the Ministry of Health announced the launch of a 3rd-dose vaccination program and a reduction of the interval between two vaccinations to 4 weeks.

How Much Do We Need a Third Vaccine Dose?

A 3rd Covid-19 vaccine dose is particularly important because the first vaccines administered in Turkey were China's Sinovac vaccine. This vaccine is known to produce a weaker immune system response to the coronavirus.

Some vaccines, such as hepatitis vaccines, are effective for life. Vaccines such as those against polio or tetanus require booster doses at regular intervals. For influenza, a vaccine is developed every autumn to provide protection against the last three of four virus strains expected to dominate during winter.

NOTE: Variants are mutations that do not change the overall identity of a virus. Strains are mutations that give a virus a different identity. In other words, if this happens, everything starts over. Not every nucleotide change makes a virus different. Although the form resulting from genetic changes in SARS-CoV-2 called Delta is described by some as both a variant and a strain, it is predominantly called a variant.

Covid-19 has been with us for such a short time that we still do not know how long immunity lasts after infection or vaccination. As with influenza vaccines, to protect against winter waves and new variants, we appear likely to need annual booster doses of the Covid vaccine. Research has therefore begun to resolve questions about whether a third dose will provide better protection against the coronavirus and what effects combining different vaccines might have.

Research suggests that the BioNTech vaccine may provide protection for at least 12 months. Following two BioNTech vaccine doses, antibody levels peak at month 3 and then fall slightly before remaining stable for up to 12 months. This can, of course, vary according to a person's age, other illnesses and medications.

The Antibody Response Persists for Up to 1 Year in People With a Previous Infection

In June 2021, Nature published study results showing that the antibody response to SARS-CoV2 persisted for at least 1 year in people who had previously had Covid-19. Among those who subsequently received an mRNA vaccine, the antibody response was also significantly strengthened, including the humoral immune response against variants of concern. According to this study, the strongest immune response was therefore seen in people who had an infection and were then vaccinated.

Studies of a 3rd (Booster) Dose

A preliminary report of a booster (third) dose study in 75 participants who had received their first two doses 8-16 weeks apart stated that antibody levels 28 days after the third dose were significantly higher than 28 days after the second dose. The antibody level was 1792 tIgG EU after the second dose and 3746 tIgG EU after the third dose.

Effectiveness Against Variants Increases After the 3rd Dose

Antibody titers binding to the beta variant also increased significantly after the third dose, and neutralizing antibody titers against alpha, beta and delta variants were higher after the booster than after the second dose. The United Kingdom announced plans for vulnerable people to receive booster doses in autumn, before winter. Turkey has also just announced the start of booster vaccination for people over 50 and healthcare workers.

Another booster-dose study involved people who had undergone solid organ transplantation and were taking immunosuppressive drugs to support tissue compatibility. In the study of 658 patients, 46% of participants did not develop an antibody response despite receiving two mRNA vaccine doses. The study evaluated a third dose of an mRNA vaccine (Pfizer-BioNTech) or an adenovirus vaccine (AstraZeneca) in people who had received two mRNA doses. After the third dose, the antibody response in organ transplant recipients whose immune systems were suppressed with medication rose to around 70%.

Is Sequential Administration of Different Vaccines an Advantage?

A study in Spain showed that both the Oxford-AstraZeneca and Pfizer-BioNTech Covid-19 vaccines produced a strong immune response to SARS-CoV-2 in humans. Several European countries were emphatically not recommending a different Covid-19 vaccine as a second dose after an initial AstraZeneca dose. However, researchers hope that mixed Covid-19 vaccination regimens will trigger a stronger and more robust immune response than two doses of a single vaccine type, and that using different vaccines will simplify immunization efforts in countries facing a coronavirus wave.

For this reason, choosing BioNTech after 2 Sinovac doses is also expected to produce a stronger immune response.

The study at Vall d'Hebron University Hospital in Barcelona, Spain, included 663 people who had received AstraZeneca as their first dose. Two-thirds received the mRNA vaccine produced by New York-based Pfizer and Mainz-based BioNTech 8 weeks after their first dose. Study researcher Magdalena Campins reported that the Pfizer-BioNTech booster appeared to stimulate the immune systems of participants who had received Oxford-AstraZeneca. After this second dose, participants began producing much higher antibody levels than before, and these antibodies recognized and neutralized SARS-CoV-2 in laboratory tests. Control participants who did not receive a booster had no change in antibody levels. This is exactly what researchers hoped and expected from mixing vaccines.

When Should Cancer Patients Receive a 3rd Vaccine Dose?

For patients receiving active cancer treatment, there is no clear restriction on when they should receive a Covid-19 vaccine; the common recommendation is therefore to be vaccinated at the first opportunity. However, patients receiving chemotherapy may prefer vaccination 1 week afterward, since they may experience side effects for several days after chemotherapy. Other special situations, such as vaccination during a period of low white blood cell counts (leukopenia, neutropenia), should be discussed individually with your oncologist.

Patients who have completed cancer treatment should receive their 3rd vaccine dose at the first opportunity.

Concern About Side Effects

A United Kingdom study analyzing combinations of the same two vaccines showed that people in mixed-vaccine groups had higher rates of vaccine-related side effects, such as fever, than people receiving two doses of the same vaccine. In the Spanish study, mild side effects were common and similar to those seen with standard Covid-19 vaccination regimens.

• Related topic: Arm Pain and Headache After the Biontech Vaccine: Why Side Effects Occur and How They Are Treated

Conclusion

Offering a 3rd vaccine dose to people over 50 and healthcare workers in Turkey is a pioneering development. Stronger immunity is expected especially when people who received Sinovac for their first 2 doses receive BioNTech as their 3rd booster dose. However, Sinovac can also be used for the 3rd dose because of individual preferences or concerns. mRNA vaccines such as BioNTech have now been administered to millions of people worldwide and have a well-known safety profile. We view this development, which could prevent Covid-19 from taking an even greater toll, very positively. People receiving a 3rd dose can be vaccinated without following a different procedure or taking extra precautions compared with their first 2 doses.

The most common side effects of Covid vaccines are pain at the injection site and headache. Pain can be relieved with over-the-counter painkillers such as paracetamol or nonsteroidal anti-inflammatory drugs . Adults can take 2 tablets of 500 mg paracetamol (for example, Parol) for arm pain and headache.

Not everyone experiences side effects after COVID-19 vaccination, and their severity and variety differ. Solutions should therefore be considered according to the person and their symptoms. Taking simple painkillers and resting is the best solution. Side effects that are unexpectedly severe and prolonged should prompt a visit to a healthcare facility.

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RELATED TOPICS

• Current Covid-19 Statistics for the World and Turkey
• Latest News and Scientific Developments About Coronavirus

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