The UK government is to step up its efforts to fight coronavirus variants by doubling the capacity of its Porton Down laboratories to test vaccines against new strains.

The government announced on Wednesday a £30m investment in new labs that will assess the effectiveness of vaccines against so-called “variants of concern”, underscoring worries that new strains of coronavirus pose the greatest threat to the UK’s current success in controlling Covid-19’s spread.

While there are growing signs that hospitalisations and deaths from Covid-19 will fall further in the UK, concerns persist that a variant could render the current crop of vaccines ineffective.

The new labs will be based at Public Health England’s Porton Down research facility in Salisbury, south-west England — better known for the Ministry of Defence’s top secret military laboratory and chemical weapons research centre.

The government said the new labs would help to accelerate the adoption of vaccines found to work against new variants. It added that it would also expand the volume of blood tests to measure the levels of Covid-19 antibodies produced by different vaccines against various variants, from 1,500 to 3,000 samples a week.

The £29.3m of funding announced on Wednesday is in addition to the £19.7m committed to the expansion of clinical testing of vaccines against variants by January 2022.

Matt Hancock, health and social care secretary, said the extra investment would “future-proof” the country from the threat of new variants.

The UK sends nearly every positive Covid-19 test for genomic sequencing, a complex process that enables scientists to identify the exact genetic code of the virus, showing just how seriously it is taking the threat.

There are four so-called “variants of concern” in the UK, including B.1.1.7, first identified in Kent, B.1.351 from South Africa, and P.1 from Brazil. The fourth is B.1.1.7 with a further mutation called E484K.

To date, scientific research has focused on B.1.351, which showed signs of being able to evade vaccine-induced immunity as a result of mutations around the spike protein that it uses to enter human cells. The fact that it could infect some of the vaccinated population may enable it to become more dominant.

There are also some signs that P.1 can evade the natural immunity conferred by previous infection with an earlier strain of Covid-19.

“The general consensus at the moment is that all vaccines will have some efficacy against these two [variants, P1 and B.1.351], and in particular in preventing severe disease,” said Sharon Peacock, professor of public health and microbiology at the University of Cambridge, who heads the Covid-19 Genomics UK (Cog-UK) consortium.

These two variants have not yet spread at an uncontrollable rate in the UK, in part because of rapid surge testing and contact tracing being rolled out wherever cases have been found.

To date, 737 cases of the B.1.351 variant and 82 cases of the P.1 variant have been identified in the UK.

Surge testing is currently being carried out in the London boroughs of Redbridge, Hounslow and Tower Hamlets, as well as neighbourhoods in Birmingham and neighbouring Sandwell.

The B.1.617 variant, first identified in India and linked to the severe wave of Covid-19 sweeping that country, has also been found in hundreds of individuals in the UK. The strain has not yet been classified as a variant of concern, however, and the scientific community is unsure whether it has any competitive advantage over other strains.

“Looking ahead, we need to study new variants very closely, particularly when the majority of the population have been vaccinated, and identify variants that could pose a greater threat to current vaccines,” Peacock said.