ON December 2, the UK’s Medicines and Healthcare Products Regulatory Agency (MHRA) authorised the first Covid-19 vaccine. After so much suffering and so many deaths from the disease, alongside the harms caused by lockdowns, this was the good news. But there were still many questions. Would this vaccine and others be effective outside of clinical trials? Would they be safe when administered in the general population? Was Scotland ready for vaccine roll out? Would uptake be good enough? Would vaccines prevent transmission of the virus?

Three months on, we have some answers. None of them are definitive and questions remain, particularly about the longer term. But the answers give us hope.

There are three vaccines that have received temporary authorisation from the MHRA so far. Temporary authorisation means approval for a year while further information is provided by scientists and the pharmaceutical companies, leading to what’s called a standard marketing authorisation that usually lasts for five years and can be extended after that. Temporary authorisation is only granted on the basis of robust results from late stage trials.

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The three vaccines authorised so far in the UK are from Pfizer-BioNTech, Oxford-Astra Zeneca and Moderna. All were tested in trials involving tens of thousands of participants with very promising results for preventing disease. The first two vaccines are now being rolled out in Scotland and it is expected that supply of the Moderna vaccine, already being used in other countries, will be available later this Spring.

Trial results and review of these by the MHRA and the Committee on Human Medicines show that the vaccines are safe and effective. But efficacy shown in carefully controlled clinical trials does not always result in effectiveness in the real world. We now have studies comparing outcomes between people who have received their first dose and those who haven’t.

In Scotland, EAVE II is an ongoing project that uses patient data to track vaccine roll out in real time. Last week the research team published a paper looking at vaccine effect since the programme started and up to February 15. They compared outcomes for people who had received their first dose and those who had not.

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The study found that by four weeks after the first dose the Pfizer vaccine reduced the risk of being admitted to hospital by 85% and the Oxford-Astra Zeneca vaccine by 94%. For those aged over 80 there was an 81% reduction in hospitalisation.

In England, a further study from Public Health England found a similar 80% reduction in hospitalisation for over-80s from either vaccine. The same study found that the vaccines provided protection against developing symptomatic disease and, for the Pfizer vaccine (which was rolled out first), an 83% reduction in deaths. These are hugely encouraging results. But research is needed that looks at the durability of this impact, and effect of two doses of the vaccine. These studies have only been published as pre-prints, which means their findings still need to be peer-reviewed by independent experts.

Examining the safety of the vaccines was a key part of the MHRA approval process. They are now publishing regular Covid-19 safety reports. These are based on the Yellow Card system which is a medicines safety monitoring mechanism. The most recent report covers the period from December 9 up to February 14. It shows that only very few side effects are emerging – between 3 and 5 reports per 1,000 doses of vaccine. Almost all of these reported side effects are mild and are not dissimilar to those from the seasonal flu vaccine. This monitoring will continue and the people who took part in the original trials are being carefully followed up to look at any long term effects.

Another question was how well the vaccine programme would be rolled out in Scotland. Delivering a programme of this scale is a huge undertaking. There have been a few bumps in the road so far, with unfavourable comparisons between Scotland and England in the early weeks when the pace was slower here.

Scotland focused initially on residents in care homes and there are early signs that the first dose may already be making a difference in these settings, alongside staff testing and public health measures. Covid-19 deaths in care homes have declined by over 60% in recent weeks.

Current concerns have been about the supply of the Pfizer vaccine, with a decline in daily doses in mid to late February. Supply is expected to increase in future. Uptake has been excellent so far and better than the 80% expected by the Scottish Government in their delivery plan. In fact more than 95% of people over the age of 65 have now received their first dose. Whether this high uptake can be maintained in younger groups, and whether there are inequalities in access or uptake between different ethnic communities or in more deprived areas, is something we need to watch and address.

One of the big remaining questions is whether vaccines will help prevent transmission. If vaccines only stop illness, then everyone needs vaccinated to be protected. But if they also stop transmission, everyone vaccinated can protect other people as well, which will help us ease restrictions with more confidence.

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There are encouraging signs, including from a Cambridge study which found a significant fall in infections 12 days after the first dose in research that tested health care staff. More evidence is needed but many studies are underway that will tell us more in future. The need for other public health measures alongside vaccines will continue for some time to come, but we can now see a cautious route out of this pandemic.