The COVID-19 booster vaccine is part of the plan, but it’s not yet clear who and when to give it.

Only 43% of Australia’s adult population is fully vaccinated with COVID-19, and millions are still waiting for a second vaccination.

However, many Australians have begun to ask about booster shots due to reports of weakened immunity and breakthrough infections in people vaccinated abroad.

Israeli health officials first began offering a third dose of Pfizer vaccine to seniors and health care workers in early August, and have since received a second COVID-19 jab more than five months ago. We provide booster shots to everyone.

In the United States, the third dose of Pfizer and Moderna vaccines Only allowed for some people with weakened immunityHowever, waiting for FDA approval, it is expected to be soon rolled out to most Americans eight months after vaccination.

Speaking last month Health Minister Greg Hunt suggested that boosters are likely to be available in Australia 12 months after the person’s first vaccination...

But is a third dose really necessary, as studies have shown that the COVID-19 vaccine is more than 90% effective in preventing severe illness and death?

And what does the deployment of booster shots mean for billions of people around the world who haven’t even received the first COVID-19 vaccine?

The third dose and booster are not always the same

It may sound like semantics, but there is an important difference between the third vaccine given as part of the first round of vaccination and the booster shots given when vaccine immunity weakens. I have.

Most countries receiving a third dose of COVID-19 prioritize people with a weakened immune system, such as cancer patients and organ transplant recipients. Those who tend to produce a weaker response to two doses of the vaccine..

These supplemental jabs should be considered as a third dose of the primary COVID-19 vaccination schedule, not as a booster, says Nick Wood of the National Center for Immunization Research and Surveillance.

“Your main course [of vaccines] It’s about getting over the high jump bar, “said Dr. Wood, a child health expert at the University of Sydney.

“Some people may need three doses on their major course to get them over the bar.”

Studies show that most of the breakthrough infections occur in people with a weakened immune system.

According to Professor Kim Malholland of the University of Melbourne, it is not uncommon for the vaccine to be given in three consecutive doses, with a gap of several months between the second and third injections.

In general, experts say that a third COVID-19 shot is needed for people with severe immunodeficiency and may also be needed for older people who are less likely to initiate a strong immune response to the vaccine. I agree with you.

Some experts even suggest that the primary course of the COVID-19 vaccine could be extended from two to three as researchers learn more about how to maximize the effectiveness of the vaccine. ..

Professor Mulholland, a member of the WHO Strategic Advisory Group on Immunization, said:

However, both the European Center for Disease Prevention and Control and the World Health Organization have emphasized that it is not currently necessary to give a third dose to people without underlying health.

“The highest-risk population with evidence of weakened immunity to severe illness and death may require a third dose,” said WHO Director Tedros Adhanom Ghebreyesus. increase. Said last week..

“But for now, we don’t want boosters to be widely used for healthy people who are fully vaccinated.”

Is the vaccine’s immunity weakened? Are Booster Shots Useful?

The data consistently show vaccine-induced protection against severe illness, and even against delta mutants, mortality remains strong for several months after vaccination.

But Israeli health officials have made progress with booster shots for the general public anyway, In fear that vaccines provide protection against infection and protection against suffering from mild illness is diminishing over time..

“Even at 6 months, the protection against hospitalization and death is very good, but the immune system may be slightly weakened. [against symptomatic infection] … It went down from about 90% to 65%. “

In Israel Preliminary data It suggests that people vaccinated in April and May are more protective against infection than those vaccinated in January.

However, it distinguishes how much this debilitating effect affects the vaccine and how much it is affected by elevated delta variants, relaxation of restrictions, and the health of the first vaccinated people. That is difficult. There is a fundamental health condition.

Pfizer recently reported that a third dose of the vaccine increased blood antibody levels against SARS-COV-2, including delta.

However, it is unclear exactly what this means for protection against COVID-19.

“This is where we don’t really have good evidence,” said Dr. Wood.

Increased antibody production can benefit people with a weakened immune system (by helping them overcome that “high jump bar”), but how much to otherwise healthy individuals. It’s hard to say if additional antibodies will help.

“Antibodies are important to viruses, but cell-mediated immunity is also important,” said Dr. Wood.

Whether the third dose significantly increases long-term immunity (mainly mediated by memory B cells and T cells) is still a question that needs to be answered.

In Israel, preliminary data suggest a third dose of vaccine Dramatically reduces the risk of COVID-19 infection, 2 weeks after the shot was administered. This makes sense because the circulating antibodies help the immune system prevent the virus from colonizing.

But the real question is how long will these high antibody levels produced by the booster vaccine last? And can they reduce overall viral infections in a persistent way?

Some experts specifically target delta mutants (or the dominant mutants of the day), given that current vaccines already provide strong and lasting protection against severe illness and death. It makes more sense to wait for the booster shot.

“Australia may be trying to get everyone to be fully vaccinated before Christmas, which may mean three vaccinations for people with immunodeficiency,” said Dr. Wood.

“And next year we will give everyone a booster [tailored to] A circulating variant. “

Australia’s vaccination rollout has been delayed, but Dr. Wood said the delay gives health officials here the opportunity to observe how booster shots are most often used.

“Australia is in a lucky position in some respects as it can see what is happening in the Northern Hemisphere and whether their booster programs actually lead to a reduction in breakthrough infections and better protection against disease. It is in. “

“Distribute extra life jackets while drowning others”

Scientific questions are not the only ones that need to be considered carefully.

As countries like Australia consider the potential benefits of COVID-19 booster vaccines, low-income countries still have billions of people waiting to receive their first jab.

“We plan to give out additional life jackets to those who already have life jackets, but others will drown without having a single life jacket,” said the Secretary-General of the WHO Health Emergency Program. One Mike Ryan says. Said last month..

August, WHO Request Moratorium on Management of COVID-19 Booster ShotsTo reduce global vaccine inequality and prevent the emergence of new coronavirus variants.

Dr. Wood said that the “small benefit” booster dose turned pale to wealthy countries compared to the “much more significant benefit” that the dose of the primary COVID-19 vaccine provides to people in low-income countries. He said he might offer.

“The other is that wealthy countries have stronger health care systems. They are more likely to receive oxygen and ventilation support than if they live in low-income countries,” he said. rice field.

“And prevention [afforded by] Vaccines are even more important. “

Professor Malholland agreed that the administration of booster immune vaccines poses a serious “moral problem”.

“Vaccines are so scarce worldwide that giving boosters that the country doesn’t think is necessary is certainly a waste of vaccines if we’re talking about protection from serious illness and death. “

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