Should Britain approve booster doses for broad swathes of the population? The Joint Committee on Vaccination and Immunisation (JCVI) is deciding this week, and has already advised a third dose be offered to over-11s who had severe immunosuppression at the time of their first or second jab (including people with conditions such as leukaemia). Approving a mass booster programme would bring Britain in line with countries such as the United States and Israel that are already offering third doses to their vaccinated populations.
These plans are based on concerns that the protection offered by vaccines may wane over time. 確かに, data from a widely cited study in Israel has shown that the efficacy against severe disease of the Pfizer vaccine decreased from 91% in individuals aged 60 or over who were vaccinated four months prior to the study, に 86% in those vaccinated six months before the study. にとって 40- to 59-year-olds, the protection against severe disease dropped from 98% に 94%.
But while these results suggest a decline in vaccine effectiveness over time, they also show that vaccines remain highly effective against severe disease six months after two doses. In a study of more than 7 百万人 イギリスで across 718 English general practices, antibody levels in the blood of people with immunosuppression gradually reduced after receiving a Covid-19 vaccination. Despite this, vaccines remained effective at preventing clinical disease – suggesting that antibody levels may not tell the whole story of how our immune systems respond.
Why is this? Primarily, we can’t yet be certain about the best way to measure the protection offered by Covid-19 vaccines. The markers of protection against getting infected with the virus that causes Covid, becoming ill with it, or becoming severely ill (resulting in hospitalisation or death), may all be different. Although antibody levels in the blood provide us with an indication of how that person’s immune system responded to the vaccine, they don’t necessarily tell us how an individual’s immune system will respond when encountering the virus.
The immune system is a complex attack system that behaves differently in different people. Measuring antibody levels to tell us how effective a vaccine will be at protecting someone from severe Covid may turn out to be the equivalent of assessing the strength of an army based on its number of tanks, rather than the full might of its forces and armoury.
With this uncertainty in mind, the World Health Organization (WHO) has called for a moratorium on Covid-19 booster shots. It has pointed out that there isn’t enough compelling science to approve boosters yet. Mike Ryan, director of the WHO’s health emergency programme, has likened plans for administering boosters to handing out “extra lifejackets to people who already have lifejackets, while … leaving other people to drown without a single lifejacket”.
By the end of August 2021, 57% of adults in high-income countries had received at least one dose of a Covid vaccine. イギリスで, this figure exceeds 88%. Yet in low-income countries, ただ 2% of adults had received one or more doses (in Benin, Madagascar, Turkmenistan and Tanzania, among other countries, less than one in 100 people had received a single dose). I’m an intensive-care physician; because of this, I received my first Covid vaccine dose in early January 2021, followed by a second dose in late March. Months later, healthcare workers in other regions of the world are still having to care for patients who have Covid, risking their lives without vital vaccine protection.
Vaccine supplies are not currently limitless, and ensuring the infrastructure is in place to deliver them across the world requires careful planning. Countries need to know in advance when supplies will be arriving so they can plan for where and how to deliver doses. It’s not helpful for high-income countries to donate vaccine supplies at short notice that they cannot use due to short expiry dates. There needs to be proper global cooperation and coordination to ensure no doses are wasted.
That so many people still lack access to vaccines because of where they live is a failure of international leadership. This unequal situation is in nobody’s interests: high levels of transmission make it more likely that new variants may emerge that evade the protection of our current vaccines. To ensure everyone is safe – including people in high-income countries – vaccinating as many people as quickly as possible is a far better strategy than vaccinating a small group of people repeatedly.
Not doing everything possible to ensure treatments, ワクチン, tests and oxygen are available to everyone who needs them is a choice. Britain will be choosing to ignore the needs of those in poorer countries if it starts administering booster shots across wide swathes of the population. All choices have consequences, and the consequences of this choice will be felt by all of us, wherever we live. There should be no room for nationalism during a global public health crisis.