Politicians have been talking a lot about lights at the end tunnels this week, after the pharmaceutical giant Pfizer said its prototype coronavirus vaccine was more than 90 per cent effective.

Researchers working on a vaccine in Russia quickly announced very similar results, leading to speculation that several working vaccines could be available soon.

There has been a flood of misinformation online about vaccines in recent years. But people also have legitimate concerns about safety, given the rush to bring out the first effective vaccine.

We’re going to find out:

• which vaccine candidates are leading the race, how good is the evidence for each and when we can expect to get a vaccine
• whether corners have been cut in trials that test for safety
• if misinformation could hamper efforts to immunise the world against Covid-19

Why is it so important that we get a vaccine?

The coronavirus has infected more than 50 million people around the world and killed well over a million. There is no sign that the global pandemic is slowing down.

Although doctors have more treatment options than they did at the start of the outbreak, there is no cure for Covid-19.

Doctors and scientists around the world are almost unanimous that a vaccine would be the best way of halting the pandemic, saving lives and gradually allowing the world to return to normality.

Vaccines trick the body into thinking it has been infected, provoking the immune system to produce antibodies that protect the individual against real infection.

For vaccines to be completely effective, enough people need to have that protection to prevent the virus spreading. If there are not enough susceptible people left to infect, the illness will die out.

With an illness as widespread as Covid-19, enormous numbers of people will have to be vaccinated across the world to eradicate it, leading to enormous logistical challenges.

But the pharmaceutical industry, governments and international organizations have been planning for the arrival of a vaccine for months.

And even if limited supplies are available immediately, vaccinating those people who are most likely to fall seriously ill or die from Covid-19 could save lives immediately.

What are the leading vaccine contenders?

There are now 48 potential vaccines going through clinical trials around the world, according to the World Health Organization.

Most of the attention is focused on Pfizer’s candidate, which uses genetic material called “messenger RNA” and on two “viral vector” vaccines being developed by Russia’s Gamaleya Research Institute and by Oxford University with AstraZeneca.

We would normally expect all vaccines to go through three phases of clinical trials before the makers ask regulators to let them market the drug.

In most trials, a group of people are given the vaccine and another group are given a placebo. A good trial will be “double blind “, which means that neither patients nor researchers know who has been given the placebo or the real thing.

The hope is that the people who got the vaccine will be less likely than those in the placebo group to catch the virus.

That’s what early results from Pfizer’s Phase 3 trials show: of the 94 people who tested positive for coronavirus, almost all were in the placebo group, leading the researchers to claim more than 90 per cent efficacy.

Russian scientists claimed a similar efficacy for their Sputnik V vaccine soon after Pfizer, based on a much smaller number of cases: only 20.

These are interim results and it’s possible that the final efficacy data will be lower. But a claimed success rate of more than 90 per cent is encouraging when you consider that the US Food & Drug Administration (FDA) regulator considers a vaccine to be successful if it prevents disease or decrease severity in 50 per cent of people.

The Oxford/AstraZeneca team haven’t reported interim results from its phase 3 trial yet. They say they hope to do so before the end of the year.

To be clear, this doesn’t mean that the Russian research is at a more advanced stage than other vaccine projects, but that the Moscow researchers have chosen to release promising data early in the process.

In fact, the Russian team seems to be significantly behind Pfizer, who say they will have enough safety data by the third week of this month to apply to the FDA for emergency use authorization. It’s not clear when the Oxford or Russian vaccines will complete their phase 3 trials.

Has the safety process been rushed?

In a worldwide race to come up with the first vaccine, it’s fair to ask whether all the normal safety procedures have been followed, or whether some corners have been cut.

There are really two questions here: have clinical trials been done properly, and will vaccines be released to the public before the normal trial process has finished?

We already know the answer to the second question, because the Russian government approved the Sputnik vaccine for use in the general population back in August, before it had undergone proper safety testing.

The move led to outrage from scientists around the world. Shortly afterwards, nine leading drug companies put out a joint statement saying they would only submit a vaccine for approval “after demonstrating safety and efficacy through a Phase 3 clinical study”.

Drug companies insist they have streamlined the clinical trials process but are using the same safety protocols they would follow in normal times.

In some cases, pharmaceutical companies have made agreements with state regulators for a “rolling review” process. This means the regulators have access to data from trials as it comes in.

This should hopefully cut the time the regulator needs to decide whether to approve the drug, without compromising safety.

We can see that large numbers of people have been enrolled for the leading Phase 3 trials. Pfizer are testing 43,538 people, the Gamaleya Institute has more than 40,000 volunteers and Oxford/AstraZeneca have enrolled about 50,000 globally.

These numbers are all well within the normal range for Phase 3 vaccine trials, as this survey of recent vaccine trials from the US shows.

It remains the case that some of these vaccines could be rolled out to tens of millions of people or more based on data from only a few hundred confirmed Covid-19 cases.

Some scientists have criticised the design of some of the trials, saying there won’t be enough data at the end to tell us how vaccines will affect asymptomatic transmission, seriously ill patients and vulnerable people like the elderly and those with underlying health conditions.

Will enough people take it?

Anti-vaccine misinformation has been a constant presence on social media for years.

It’s not possible to guess the motivation of everyone who spreads false stories about vaccines. But Britain’s chief of defence staff, a Times investigation and academic researchers in the US have all found evidence that Russia is behind some of the fakery, even as it is battling its own Covid crisis and trying to create a vaccine.

Could vaccine scepticism become so widespread that large numbers of people refuse to have themselves immunised?

A survey of more than 1,200 people published today by the London School of Hygiene & Tropical Medicine (LSHTM) found that almost 90 per cent of parents and guardians said they would definitely or probably have themselves and their children vaccinated against coronavirus.

But other evidence is emerging that suggests people who are exposed to online misinformation may be less likely to have themselves vaccinated.

One troubling finding in the LSHTM study is that people who described themselves as Black, Asian, Chinese, Mixed or Other were almost three times more likely to say they would reject a COVID-19 vaccine than people who gave their ethnicity as white.

This comes as more evidence emerges of people from ethnic minorities being at higher risk from Covid-19.

Do vaccines change human DNA?

A leading example of misinformation is the idea that the mRNA technology used by Pfizer could lead to changes in the human genome, a fear that has been raised in countless online memes.

Experts in the field squarely reject this idea, based on current evidence.

An mRNA vaccine uses a small piece of genetic material from the virus called messenger RNA to instruct cells in the human body to start making viral proteins.

In a Covid-19 vaccine, cells are instructed to make “spike proteins” – the structures the coronavirus uses to enter host cells. The immune system then makes antibodies to deal with them, offering protection against future infection by a virus using the same proteins.

An mRNA vaccine works in a completely different way to the “viral vector” approach used by the teams from Oxford and Moscow. These vaccines use weakened versions of other viruses as vehicles to shuttle the coronavirus spike protein code into cells and provoke an immune response.

The sound of introducing genetic material to the body might sound strange, but it’s a fact of human life that we are exposed to RNA and DNA from foreign bodies all the time – from viruses and other pathogens and even the food we eat.

The RNA is a limited piece of genetic material is designed to perform a specific task. It does not stay in the body for long.

RNA is chemically different to DNA and scientists say there is no realistic risk of it integrating into human DNA.

Darren Griffin, Professor of Genetics at the University of Kent, told us: “DNA makes RNA, and RNA makes protein – this the is ‘central dogma’ of molecular biology. Put simply, the RNA in these vaccines does not enter the genome.”