Throughout the last couple of weeks, the efficiency of particular vaccines has come under question as new Covid-19 strains are analysed, and countries begin to roll out their vaccination programmes.

Stats show that worldwide new variants are quickly dominating infection cases compared to the old strain; Doctor Eric Feigl-Ding, an epidemiologist and chief health economist for Microclinic International, described it on Twitter as the beginning of two different diverging pandemics.

For example, in Denmark and a few localities in Italy, the British B117 variant has been seeded and is rapidly rising and replacing the old strain, which is sharply declining. Therefore, Dr Feigl-Ding and Independent SAGE have argued that a zero-Covid strategy is the only answer in the medium-term to prevent an increasing acceleration of infection, combined in the longer-term with mass vaccination.

An article discussing the necessity for combining these two strategies was published in Bloomberg Opinion. The author used the example of Israel, which has had the fasted vaccination programme, having vaccinated 20% of its population. On the other hand, lockdown measures have been loosely adhered to, which has caused a continuous rise in deaths of unvaccinated older people and a rise in younger people requiring hospital treatment.

What will the new strains mean for vaccination efficiency?

Independent SAGE briefed in early January that there is no evidence that the B117 variant is resistant to the current vaccines, as the immune response generated by vaccinations works even if a specific mutation compromises a small number of antibodies. But they warned that any further modifications of the new variants might affect antibody effectiveness against the virus.

Correspondingly the University of Cambridge has this week released preliminary data that showed that the Pfizer BioNTech vaccine is likely to be effective against the B117 variant. However, a reason for concern was that higher concentrations of antibodies are required to neutralise the virus, especially when the B117’s E484K mutation was analysed.

Professor Ravi Gupta, a researcher at the Cambridge Institute of Therapeutic Immunology and Infectious Disease, said of the findings: “Of particular concern… is the emergence of the E484K mutation, which so far has only been seen in a relatively small number of individuals. Our work suggests the vaccine is likely to be less effective when dealing with this mutation.”

He added: “B117 will continue to acquire mutations seen in the other variants of concern, so we need to plan for the next generation of vaccines to have modifications to account for new variants. We also need to scale up vaccines as fast and as broadly as possible to get transmission down globally.”

Similarly, last week, Novavax and Johnson & Johnson published the results of their clinical trials that suggested that their vaccines are less effective against the new South African B1353 variant, with the Norvavax’s vaccine reaching an efficiency of 60% and Johnson & Johnson’s only getting 57%. Nevertheless, these results are still above the World Health Organisation’s recommended vaccination efficiency threshold of 50%.

Is the AstraZeneca vaccine effective in older people?

A different concern over the efficiency of the AstraZeneca/Oxford vaccine is why South Korea, as well as many European countries, have this week decided to restrict AstraZeneca's Covid-19 vaccine to people below 65, reasoning that there is insufficient data on its efficiency in over 65s as only 12% of those who took part in the AstraZeneca clinical trials were in that age group.

A similar rationale was behind the German Standing Committee's recommendations on vaccination, which last week released a report that said the AstraZeneca vaccine only be given to the age groups 18-64 as ‘there is not sufficient data to evaluate the efficiency for the age 65 and older’.

But many other countries are adopting a different strategy and have approved the vaccine in all age groups, including the UK, Mexico, Argentina, and India. Additionally, the EU’s European Medicines Agency has also authorised the AstraZeneca vaccine in all ages groups.

AstraZeneca has responded to the decision to curb the use of the vaccine by saying that the vaccine triggers an excellent immune response in older people. Previously, Professor Andrew Pollard, the chief of clinical trials for the vaccine, told the BBC last year that a robust immune response was evident in participants above the age of 65.

So, as the pandemic swiftly changes, new strains will emerge in places where infection rates are uncontrolled. Therefore the efficacy of the vaccine to combat these strains will have to be continuously re-analysed. But there is a concerning probability that some vaccines will be comprised later down the road. And as the world collects more data on the effectiveness of particular vaccines in weaker immune systems, countries will predictively adapt their vaccination strategy in light of those developments.