COVID vaccines protect against Delta, but their effectiveness wanes. Centers for Disease Control and Prevention. How long do vaccines last? The surprising answers may help protect people longer. No one can be protected from COVID-19 until everyone is protected.ġ. However, the main priority remains the same – to ensure that people worldwide are vaccinated against SARS-CoV-2.⁸ While the World Health Organization (WHO) has said that more evidence is needed when it comes to vaccine booster injections, they have recently advised that boosters may be key to help protect the most vulnerable populations such as the elderly and those who are immunocompromised, especially in light of surging infection rates.⁸ As such, some countries like Israel and the Czech Republic have established policies to implement vaccine booster injections in select high-risk populations. What’s the current guidance on vaccine booster injections? The good news is that vaccine developers have taken action, and several studies on the need for booster shots are underway. And as other SARS-CoV-2 variants arise, it is also important to ensure that these vaccine boosters can offer cross-protection against new mutations of the virus.įor now, a decline in SARS-CoV-2-specific antibodies may indicate the need for future vaccine booster injections, but more research is urgently required. These cells can quickly churn out antibodies should the virus invade.⁵ T cells also play their part by destroying infected cells and limiting the severity of disease.⁶ Vaccine boosters reactivate the immune memory and have been shown to result in a rapid rise in antibodies⁷, bracing the body to be ‘ready’ to combat infection over time. Though this sounds concerning, the immune system can also ‘remember’ the virus with memory B cells. People who have received a vaccine against SARS-CoV-2 (the virus that causes COVID-19) typically have a good level of protection against serious illness from infection, but initial research suggests that this protection may start to wane over time.⁴ In the months after vaccination, it appears that antibodies may start to decrease, making the immune response less effective against the virus in general, and the Delta variant in particular.⁴ What does this mean for the future of vaccine protection against COVID-19? That’s why scientists have called for more research into this area, arguing that if more was known about ‘vaccine durability’, better vaccines could be made.² After the initial series of four shots, received at a very young age, a booster dose is needed a few years later, with a further boost at the age of 11 or 12 years.³ĭespite advances in virology and immunology, why and how levels of immunity can fluctuate and decline over time is not well understood. One example of this is the Tdap (or DTaP) vaccine, which helps protect against tetanus, diphtheria, and pertussis (whooping cough). When that happens, months or years after the initial injection, a ‘booster’ dose is needed³ to increase the body’s immune response. What is known is that, for some vaccines, immunity begins to wear off after a while. But whether immune memory is related to the way in which a vaccine is made, or to the specific virus itself, is still not clearly understood.² Also, some vaccines can enhance the body’s ‘immune memory’ by stimulating B cells to produce antibodies (protective proteins produced in response to a virus or other foreign substance) and training T cells to help eliminate infected cells and prepare the body for a possible viral infection in the future. Most individuals will need a vaccine booster injection at some point in time, although the period between additional injections varies greatly.¹ There are several reasons why: some viruses mutate more quickly than others, which may reduce the protection offered by a first vaccination.
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