The United Kingdom has approved the use of the Pfizer/BioNTech vaccine against SARS-CoV-2, the virus that causes Covid-19, becoming the first in the world to approve a Covid vaccine for widespread use.

The Medicines and Healthcare products Regulatory Agency has confirmed that immunization can begin next week. The data from the final phase 3 clinical trial show that the vaccine, administered in two dosages, has an efficacy of 95 percent.

“The continued progress on vaccines is fantastic news. A route towards a much better situation in the UK is becoming clear. A further circuit breaker in January or possibly February is likely to be needed. But, it is realistic to hope that by March or April the vast majority of older people, care home residents, and those with severe conditions will have been immunized,” Prof Liam Smeeth, Professor of Clinical Epidemiology at the London School of Hygiene and Tropical Medicine, said in a statement.

“We can then work towards wider immunization – with ideally much of the population covered in time for next winter. Life won’t ever be the same as it was before Covid-19, but it will feel a whole lot better than now.”

Experts believe that while the vaccine will protect us, we won’t be able to consign Covid-19 to history as we did with smallpox. Vigilance and health-conscious behavior will have to remain in common use.

The UK has ordered 40 million doses of the vaccine, enough to immunize 20 million people, less than a third of its population. Workers in the National Health Service (NHS) and those most vulnerable to the disease will be the first to get the jab.

The Pfizer/BioNTech vaccine becomes the first approved mRNA vaccine. In this technique, a non-dangerous bit of genetic material from the virus (the RNA) is injected into the human body. Cells in our body take in this mRNA and use the genetic instruction to produce this viral protein. Although the protein is harmless, our immune system recognizes it as a foreign object and gets rid of it.

If the virus then enters our bodies, the immune system is primed to recognize and quickly defeat the pathogen.

The other two promising vaccines from Moderna and Oxford are also in the review process from regulatory agencies around the world. Having multiple different successful options will allow for maximum global coverage.

For long term viability, the Pfizer vaccine requires ultra-cold storage, around -75°C (-103°F), but it can be kept in the fridge for five days. The Moderna one needs to be kept in a deep freezer at -20°C (-4°F) but can remain in a regular fridge for up to six months. To remain viable the Oxford vaccine can instead be stored at fridge temperatures.