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Declining Effectiveness of COVID Vaccines and Booster Doses

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Now that COVID vaccines have reached millions of people all over the nation, there is a hearsay that the efficacy of COVID vaccines is declining. This article will navigate you through some information about the COVID-19 vaccines and the need for booster doses.

Medically reviewed by

Dr. Jagdish Singh

Published At November 13, 2021
Reviewed AtNovember 9, 2022


In this global pandemic crisis, there are several factors that affect the rise and fall of COVID cases. The several factors include the effectiveness of the COVID vaccine over time, following infection prevention protocols and changes in the Coronavirus variants, and the number of people who are vulnerable. COVID-19 vaccines are considered a game-changing tool. Cases among those fully vaccinated constituted a sizable chunk of the daily count of COVID cases. But currently we are hearing news about the declining effectiveness of the COVID vaccines, and experts are thinking about how to overcome this unprecedented situation. It just feels like yesterday where everyone was waiting for the day when they would be fully protected against the Coronavirus by their vaccination. In times of deep uncertainty, science has been asked to look to the future and to decide how to react to the declining effectiveness of the COVID vaccines. There comes a talk about the booster doses.

Declining effectiveness is something that our health experts expected to happen several months after full vaccination, but it has shocked us by happening earlier. Research says that a booster dose can significantly help restore the protective effects.

In the research, it was found that 14 days after the booster dose, there was about a 48 to 68% reduction in the person's testing positive for COVID-19.

What Is a COVID-19 Booster Dose?

COVID-19 booster dose is an additional dose of COVID-19 vaccine given after the original primary vaccination, be it single or double doses vaccines. It is given for better and effective protection. A booster dose is typically given after the immunity from the initial doses starts to wane off. The foremost aim of booster dose is to offer a longer-term immunity.

Vaccines are given to protect against severe hospitalizations or some other worst outcomes like death. So booster doses are generally recommended when there is insufficient protection against the disease over time. Booster doses are not a new idea, but since when the COVID-19 vaccines were developed, the experts have acknowledged that boosters may someday be needed.

Why Is a Booster Dose Needed for COVID-19?

Booster doses are developed to target the new developing variants of COVID-19 and to provide long-term immunity against the deadly virus. It is normal for the antibodies to wane off over time, and one great thing is that our immune system has a memory of past infections or previous vaccines. So when you are getting exposed again to something similar through a booster shot following the exposure by the original or the initial vaccination, the memory response is even more intense than the original. Hence by delivering booster doses, the protection against the disease is enhanced.

Should Everyone Take the Booster Dose of COVID-19 Vaccine?

You may need to take the booster dose if you fall under any of the following categories:

  • People above 65 years as the risk of severity of the illness increases with age.

  • People who are above the age of 18 and who have other underlying medical conditions associated with immunosuppression should take a booster dose on their individual risks and benefits. Immunocompromised conditions include:

- People who are undergoing cancer treatment.

- People who have received an organ transplant and those who are taking medications that can suppress the immune system.

- People who received stem cell transplants within the last two years.

- People with moderate to severe immunodeficiency.

- People diagnosed with HIV and who are taking any medications for HIV.

- People who take high-dose steroids.

NOTE: If you have any doubt whether you belong to the above categories, then do contact your nearby healthcare provider for details.

  • People above 18 years and who live or work in high-risk areas. People who work under the following occupational settings:

  • Healthcare professionals.

  • Firefighters.

  • Police.

  • Public transit workers.

  • Teachers.

  • Daycare workers.

  • Manufacturing workers.

  • Food and agricultural workers.

  • Grocery store workers.

  • And if you have received Johnson & Johnson vaccine.

People who have received Johnson & Johnson vaccines should take their booster dose because the effectiveness of the vaccine decreased over time when compared to the other mRNA vaccines.

When Can the Booster Doses Be Taken?

Health experts recommend taking the booster doses at least after six months of taking the second dose of the COVID-19 vaccine. And in case if the person has taken Johnson & Johnson vaccine, then the experts recommend taking the booster dose at least after two months after the original shot.

Should We Take the Same Brand of Vaccine as the Original Doses?

The Food and Drug Administration (FDA) has suggested that it is safe for individuals to receive booster doses that are a different brand than the original or initial doses (the one received for the first and the second doses). So you can choose which COVID-19 vaccine you want to receive as a booster dose because some people may prefer getting a different vaccine for the booster dose. Now the experts are allowing for the mix and match for booster doses.

Can Booster Doses Cause Side Effects?

If you have developed some adverse reactions on getting your initial doses, then you can expect some similar adverse reactions or even worse. But the studies are still going on if the adverse effects are worse or if there is a change in the adverse effects with boosters. But so far, it is considered to be safe, and the side effects of the booster doses remain low.


Booster doses should be mainly offered to the population that is in great need. Getting vaccinated cannot keep us from following other protocols such as wearing a mask, social distancing, washing hands frequently, as by doing so, we can put an end to this deadly virus as soon as possible before it roars as different variants.

Frequently Asked Questions


Is It Safe and Beneficial to Mix Pfizer and Moderna Boosters?

Healthcare officials are most confident about the interchanging of the booster doses according to past studies on mixing and matching. Certain reports say that the mixing of vaccines might enhance the immune response. Also, public health adds on to the fact that it is safe to mix Pfizer and Moderna vaccines for giving booster shots.


Does One Need to Get a Similar Type of Vaccine for the Two Doses?

One should take two doses of vaccines for attaining and realizing the full efficacy of vaccination. Healthcare providers also recommend it this way. Additionally, it is recommended that a similar vaccine should be taken in the second dose as the primary one. So, both doses should be a similar vaccine type.


Is It Fine to Mix the COVID Vaccines?

CDC (Center for Disease Control and Prevention) and other authorities do not recommend mixing the COVID vaccine products for the primary series of doses. If one received the particular type of vaccine for the very first dose of the primary series, then the individual should go with the same product for all subsequential primary series of doses.


Can One Switch From Moderna to Pfizer Booster?

Though the vaccines Moderna and Pfizer are similar, they influence the immune system in a contrary fashion. Also, there prevails no advantage of switching between Moderna and Pfizer vaccines. If one primarily received the J&J (Johnson and Johnson) vaccine, then one can consider switching to either Moderna or Pfizer shot.


Which Is Beneficial Moderna or Pfizer?

Both the vaccines Moderna and Pfizer are beneficial and effective against COVID-19 and its severe infections. Nevertheless, recent studies validate that Moderna brings about a distinct and potent immune system response. Also, it tends to be better in the prevention of breakthrough infections.


Is It Fine to Take a Pfizer Booster After Taking AstraZeneca?

The preliminary studies say that the mixing of two vaccines Pfizer and AstraZeneca can provide potent protection. Nevertheless, a group of researchers suggests that only individuals who could not take Pfizer for medical concerns or individuals who have already administered two primary doses of AstraZeneca can receive the AstraZeneca as the booster does.


Which Vaccine Is Effective Against Omicron?

The study says that the bivalent vaccine was about 58.7 % effective over hospitalization when compared to the original and monovalent vaccine, which was about 25 %. Also, this vaccine was about 61.8 % effective against infections. So, the Bivalent vaccine is considered more effective, which was designed to show protection against original SARS-COV-2 and Omicron variants.


Is Moderna Beneficial Against Omicron?

The data on new and recent studies suggest that Moderna’s booster dose of COVID-19 works really better and is beneficial against various variants of Omicron. Its ability to combat and shield against infections drops precisely when analyzing the Omicron variant.


Is the Booster Shot Similar to the First Shot?

Booster is considered an additional vaccine dose designed for individuals who are immunocompromised or have waning immunity since they are done with the primary vaccine series several months before. The booster is chiefly given after the efficacy provided by the primary vaccine series has commenced diminishing over time. The booster is the same for children aged five to eleven years, and adults are now given the new vaccine, namely the bivalent booster.


What Is the Difference Between a Booster Dose and a Third Shot?

The individuals get their third shot as soon as the appropriate days, right after the second dose. The booster is chiefly prescribed and given after the protection enhanced by the primary vaccine series has begun to diminish over time. The booster is meant to maintain immunity function.


How Long Will the Side Effects of COVID Booster Last?

The common side effects of the COVID booster include fever, headache, pain at the injection site, and body aches. These symptoms usually resolve on their own within a few days. It is the time when the body builds protection against virus-causing infections. Moreover, vaccine-induced allergic reactions are rare.


How Long Can a Booster Last?

The efficacy of the booster dose tends to diminish after ten weeks. Nevertheless, the protection and inhibiting capacity against severe diseases remains at higher intensities. This is because the protection against infection can be short-term, but the protection over severe conditions is sound and robust.


Can One Take Ibuprofen Right After the COVID Booster?

One can take Ibuprofen after the COVID booster for the relief of certain symptoms encountered after the shot, including headache, fever, and sore arm. The recommended dosage of Ibuprofen for adults can be 200 to 400 mg three or four times a day.


Is the COVID Booster Similar to the Original Vaccine Dose?

The COVID booster dose shot is a vaccine dose that is given after an individual has been done with the original vaccine shots, known as the primary series of doses. So, this is given with the concern that the protection provided as a result of the original COVID vaccine could begin to diminish or weaken over months.


Is COVID Booter Essential?

The studies and clinical researchers show that booster dose is safe and could increase the distinct neutralizing antibody levels of SARS-COV-2 which are cross-reactive to present variants of concern. The booster dose is significant for the protection of immunocompromised individuals and elderly adults since they are at higher risk of severe forms of COVID.
Dr. Jagdish Singh
Dr. Jagdish Singh

Medical Gastroenterology


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