Which Covid vaccine is better? How long does it last? The most common vaccine questions answered

As the coronavirus pandemic rages on, health officials have pushed the importance of Covid-19 vaccines in an effort to protect a majority of Americans, and the rest of the world, against the novel virus.

Already 158 million Americans, or 47.7 per cent, have received at least one dose of a Covid-19 vaccine and 124 million Americans, or 37.5 per cent, are fully vaccinated against the virus, according to data released by the Centers for Disease Control and Prevention (CDC).

Health officials would now have to reach those who are hesitant about the vaccine, as the country works to reach herd immunity. But questions still remain among some people about the available vaccines’ safety and efficacy.

The Independent has answered some of the most searched questions about the Covid-19 vaccines.

A recurring issue among the vaccine-hesitant is the difference between FDA emergency use authorisation versus full approval for the Covid-19 vaccines.

Currently, there are three pharmaceutical companies that have emergency use authorisation (EUA) for their Covid-19 vaccines: Pfizer/BioNTech, Moderna, and Johnson & Johnson.

Usually, the FDA can take one year or longer to give a drug full approval. But the pandemic encouraged the federal health agency to issue emergency use authorisation to the three different companies for their Covid-19 vaccines. The emergency use authorisation allowed for companies to apply for the approval with just two months of clinical data.

“For an EUA to be issued for a vaccine, for which there is adequate manufacturing information to ensure quality and consistency, FDA must determine that the known and potential benefits outweigh the known and potential risks of the vaccine,” the FDA states on its website.

The federal health agency has maintained, though, that safety standards were not loosened when issuing emergency use authorisation to the available Covid-19 vaccines.

“Covid-19 vaccines are undergoing a rigorous development process that includes tens of thousands of study participants to generate the needed non-clinical, clinical, and manufacturing data,” the agency said.

Pfizer announced earlier this month that it has applied for full approval for its Covid-19 vaccine in people ages 16 years and older from the FDA. Moderna has also indicated it will submit its application for full approval in the coming weeks.

If approved, the companies could then market their shots directly to consumers and possibly alter the pricing of the doses. Currently the vaccine is available for free to Americans through the federal government.

The approval would also allow the vaccines to remain on the market after the pandemic because they would no longer have “emergency” authorisation.

When Covid-19 vaccines first received emergency use authorisation in December, researchers knew little about how the jab could impact pregnant women. This was because pregnant women were excluded from initial clinical trials.

Several studies have since come to light and have shown positive preliminary results of the vaccines’ impact for pregnant women.

In one study, published in JAMA: The Journal of the American Medical Association earlier this month, Pfizer and Moderna’s vaccines sparked a robust immune response in pregnant and lactating women. The results also indicated that the vaccines protected the women against the novel virus.

Then a second study, published in the journal Obstetrics & Gynecology last week, revealed that there was no evidence the Pfizer or Moderna vaccine caused damage to the placenta in pregnant women.

Based on the current data available, the CDC and FDA have authorised the vaccines for anyone who is pregnant or planning to become pregnant. But the health agencies do recommend for women to consult with their healthcare provider if they are unsure about the potential effects of the vaccine.

“You might want to have a conversation with your healthcare provider to help you decide whether to get vaccinated. While such a conversation might be helpful, it is not required before vaccination,” CDC states on its website.

open image in gallery

According to clinical data, the Pfizer vaccine is 95 per cent effective in preventing Covid-19 disease two weeks after the second dose of the jab. Moderna’s vaccine is 94 per cent effective in preventing Covid-19 disease two weeks after the second dose.

A new study released by the CDC has also found that a single dose of Pfizer’s or Moderna’s Covid vaccine was 80 per cent effective in preventing infections.

The single-dose Johnson & Johnson vaccine is 66 to 72 per cent effective in preventing Covdi-19 disease about two weeks after the jab.

However, the company announced in September that a booster shot of the Johnson & Johnson vaccine would be 94 per cent effective when given two months after the initial shot.

So Pfizer and Moderna’s vaccines have demonstrated a higher effectiveness against the novel virus, but that doesn’t mean they are necessarily better to get.

Johnson & Johnson’s vaccine has a higher efficacy against severe disease from Covid-19 compared to its effectiveness against disease from all symptoms related to the novel virus, which health experts have called a “game changer”.

“The overall efficacy for severe disease was 85 per cent,” Dr Anthony Fauci said during a White House Covid press briefing in April. “There were essentially no hospitalisations or deaths in the vaccine group, whereas with the placebo group there were. We have a value-added vaccine candidate.”

Experts have also pointed out that none of the three vaccines have gone head-to-head in determining which was the most effective. Instead, the vaccines were tested differently in clinical trials around the world, making comparing the three jabs nearly impossible.

Pfizer’s Covid-19 vaccine is the only vaccine currently available in the US that has received emergency use authorisation for children ages 12 to 18 years old.

Both Moderna and Johnson & Johnson’s vaccine are approved for emergency use in those ages 18 years and older.

Federal health officials authorised the Pfizer vaccine for children ages 12 to 15 years old last week after clinical trials showed the jab was safe and effective against the novel virus for that age group. Since then, the US has administered more than 600,000 vaccines to that age group, CDC Director Dr Rochelle Walensky revealed on Tuesday.

So yes, the vaccines have been found to be safe in children 12 years and older.

Children are more likely to be asymptomatic or develop mild symptoms from Covid-19 if they contract the novel virus. But some children have still experienced severe symptoms or transmitted the virus to others, which is why health officials prioritised vaccinating all age groups.

Studies are ongoing about how long immunity lasts after people are fully vaccinated against Covid-19.

Recent data released by Pfizer has indicated the immunity from its vaccine lasts at least six months after the second dose. In the study, there was minimal antibody decline after six months. Similarly, results from Moderna showed that participants had a high level of antibodies in their system after six months of becoming fully vaccinated.

Critics have taken this information and concluded that it means the vaccines only offer six months of protection against the virus, but this conclusion is incorrect.

Given these are breakthrough vaccines that have only been administered to large segments of the public since December, the data is limited for researchers to determine how long immune response lasts. Experts hypothesise immune response could last months longer.

Covid-19 variants are also another variable experts are considering when determining immunity. Several highly transmissible variants are circulating the US and around the world, but there is no indication yet that these will diminish vaccine efficacy.

Pharmaceutical companies are researching potential booster shots to their vaccines that would increase someone’s antibody count in the future, which could be used if antibody count and vaccine efficacy diminish.

The Biden administration has worked alongside state governments and pharmacies to provide Americans with easy access to the available Covid-19 vaccines.

Vaccines.gov is an online website developed by the CDC to assist people in finding a location near them offering vaccination appointments. Additionally, individual states also have their own portals that detail vaccine sites in someone’s surrounding area and if appointments are available.

Large pharmaceutical chains like CVS, Walgreens, and RiteAid have also collaborated with the federal government to provide Covid-19 vaccines to customers.

Individuals looking to receive a vaccine at a pharmacy can go directly to the store’s website to set up an appointment at a nearby location.

For the most part, the CDC guidance states that fully vaccinated Americans are allowed to participate in normal activities without wearing a mask or social distancing.

"If you are fully vaccinated, you can start doing the things that you had stopped doing because of the pandemic," Dr Walensky said during a White House press briefing last week when announcing the new guidance.

According to the CDC, vaccinated individuals no longer have to wear a mask for indoor and outdoor activities, including eating at a restaurant, participating in an exercise class, and attending an outdoor event like a concert.

This same guidance also applies to social distancing.

Previous guidance recommended for vaccinated individuals to wear a mask when indoors if they were around other people who have yet to receive a vaccine. But Dr Walensky said this would no longer be required.

"The science demonstrates that if you are fully vaccinated, you are protected. It is the people not vaccinated who are not protected," she said.

"The science is also very clear about unvaccinated people: you remain at risk of mild or severe illness, of death, or of spreading the disease," Dr Walensky added. "You should still mask, and you should get vaccinated right away."

The CDC still requires all Americans to wear masks when on aeroplanes or other public transportation like trains and busses.