皇家华人

鈥淚t鈥檚 not possible to stop everybody getting it, you can鈥檛 do that, and it鈥檚 also not desirable because you want immunity in the population to protect ourselves in the future鈥�. Not long after Patrick Vallance, the UK鈥檚 chief scientific adviser, spoke these words on 12 March 2020, East Asian countries showed that epidemics could be crushed through strong public health measures.

Our Scientific Advisory Group of Experts (Sage) was 鈥渦nanimous鈥�, however, that these countries would inevitably face a huge second wave. The impact of the UK鈥檚 鈥渓iving with the virus鈥� policies has included 153,000 excess deaths and 拢372bn of additional government spending owing to the economic crisis (GDP collapsed by 9.9 per cent in 2020). The debate now is to what extent the UK鈥檚 impressive vaccine roll-out has changed the equation of risks and benefits. Were Tory backbenchers and Sajid Javid right to hurry England out of lockdown on 19 July?

In the short term, Javid鈥檚 move has made things worse. We already have among the highest per capita case rates in the world, rising hospitalisations, and a slow increase in deaths. The apparent message that infections don鈥檛 really matter may also worsen vaccine hesitancy. Nonetheless, the latest data suggests cases have peaked (rates have fallen for five consecutive days), while hospitalisations are within the capacity of the NHS and deaths remain below 100 per day. Our media might soon be congratulating Javid on his 鈥淏ig Bang鈥� approach.

But the true question for the UK, and for the world, is whether we move to a relatively mild 鈥渆ndemic state鈥� or one where severe epidemics wax and wane over several years. We still face a mutating virus that is more virulent and transmissible than influenza. Will cases and hospitalisations surge again in the winter? Will vaccine benefits last long enough to reach 鈥渉erd immunity鈥�? Can we vaccinate the world to restore the free flow of people and goods?

When we vaccinate against stable viruses that don鈥檛 mutate, such as measles, mumps and rubella, we gain both antibody and T-cell protection. If you meet the virus again after vaccination, your T-memory cells will stimulate a boosted antibody response and killer T-cells will eliminate infected cells before the virus replicates. The biology of the Covid virus, Sars-CoV-2, is very different though. Anthony Leonardi, an immunologist at Johns Hopkins University in Maryland, US, believes the virus 鈥渄istorts T-cell function, numbers and death, and creates a dysfunctional immune response鈥�.

It makes a protein that enables infected cells to 鈥渃loak鈥� themselves from killer T-cells, giving the virus precious time to replicate. This means that neutralising antibodies, which have an immediate effect, are critical to prevent mild and moderate illness. These antibodies cover the whole spike proteins of the virus when exposed at a cell鈥檚 surface, allowing other natural killer cells to stop the virus in its tracks.听

But the duration of antibody levels capable of neutralising Sars-CoV-2 is relatively short, and even shorter in older people. New lab evidence shows that the AstraZeneca vaccine produces much lower levels of neutralising antibodies for the Delta variant compared with the original Wuhan virus.

Even fully vaccinated people can still become infected, albeit less seriously for now. New variants might show greater 鈥渧accine escape鈥�. Breakthrough infections in Israel, Gibraltar and in the UK (where they account for more than one-third of hospitalisations) suggest an annual booster jab will be needed with an updated vaccine for most of the world鈥檚 population.

Emerging research is showing how little we know about the long-term effects of Covid. In common with Ebola, rabies and HIV, the Covid virus possesses a 鈥渟uperantigen鈥�, a peptide (a short chain of amino acids) capable of activating T-cells not specific to the virus. This activation can manifest in autoimmunity and organ damage, as seen in the multi-inflammatory syndrome which has put thousands of children worldwide into intensive care. A new study of 80,000 adults showed cognitive decline in those who鈥檇 had Covid after controlling for age, sex and education, with deficits present that did not depend on time since infection.

The latest ONS survey of Long Covid found that 962,000 people, after a first infection, experienced self-reported symptoms of fatigue, shortness of breath, 鈥渂rain fog鈥� and muscle aches, persisting for more than four weeks. A sub-study of 20,000 showed 13.7 per cent had symptoms for more than 12 weeks, eight times higher than uninfected control participants.

The decision of our Joint Committee on Vaccination and Immunisation not to recommend vaccinating 12-17-year-olds (even though the Medicines Regulatory Authority has provided approval) plays down this evidence of longer-term risks. Most cases are mild in children but even a small percentage developing Long Covid and cognitive problems could lead to large numbers affected. We urgently need more research on cohorts of infected children.

Further, global vaccination is progressing very badly, with just 13.7 per cent of people fully vaccinated worldwide, and only 1.6 per cent in Africa. The world鈥檚 27 poorest countries have received just 0.3 per cent of vaccine doses worldwide.

Most countries helped by the Covax system 鈥� the World Health Organisation's vaccine initiative 鈥� depend heavily on the AstraZeneca jab manufactured by the Serum Institute of India. But India has blocked exports of the vaccine. Official death rates conceal the scale of the growing disaster among unvaccinated populations. In India alone, a new study estimates excess deaths to be in the range of 3.4 million to 4.7 million 鈥� about ten times higher than the country鈥檚 official Covid-19 death toll.

With Germany, Canada and the UK blocking President Joe Biden鈥檚 proposal of a vaccine patent waiver, G7 countries are guilty of both hoarding vaccines and blocking others from producing them at scale, a moral and geopolitical failure that lower income countries will not forget. Some have turned to the Russian Sputnik vaccine and China鈥檚 Sinovac, although there are still concerns about their supplies and regulatory standards.

Despite the UK鈥檚 higher coverage, a vaccination-only policy does not guarantee success. We are still without an effective local public health system to crush new outbreaks, our health service must cope with unpredictable numbers of future Covid-19 casualties as well as the huge backlog of patients on hospital waiting lists, and vaccine passports face stiff parliamentary opposition. A global economic recovery will depend upon a coordinated international response that has so far failed to materialise and the hope that the virus mutates into a milder pathogen.

This article was first published in听 on 26 July 2021.

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• Original article in听
• 听
• UCL Institute for Global Health
• UCL Faculty of Population Health Sciences