Coronavirus US: Are all vaccines effective against the Lambda variant?

In recent months the various mutations of covid-19 have grown in significance across the world, with the recent surge in cases in the United States attributed to the Delta variant.

In November 2020 the Lambda variant, also known as C.37, was first sequenced by scientists in Peru and it has taken a foothold in the country since then. In April this year the variant was identified in Texas but it has not reached the rate of infection that the Delta variant has managed.

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Is the Lambda variant resistant to covid-19 vaccines?

Given the fairly small number of cases in the United States it is hard to draw any solid conclusions from the evidence gathered, but the comparative experience of Peru does suggest that different vaccines may offer very different levels of protection.

Peru’s vaccination effort has relied on use of the Chinese-manufactured Sinopharm vaccine, which is only around 79% effective at preventing hospitalisation. In comparison, the Pfizer and Moderna shots used most commonly in the US are around 94% effective against hospitalisation.

Researchers in Japan have studied the Lambda variant and found that mutations in the virus’ spike protein may have helped it resist vaccine-induced antibodies in patients. They contend that this has helped to make it particularly infectious and enabled it to infect some vaccinated patients.

But while researchers have suggested that the Lambda variant is more infectious than the original strain of covid-19, the efficacy of the vaccine may have a large part to play in that. For now, the US has reported just 1,300 cases of the Lambda variant. This may be due to the more effective vaccines preventing the spread.

Lambda designated as ‘variant of interest’

The World Health Organization (WHO) has created a three-tier variant classification system: ‘variant of interest’; ‘variant of concern’; and ‘variant of high consequences’. Lambda is currently in the lowest of the three categories, ‘variant of interest’, which means that scientists suspect that it may be either more infectious or be able to surpass vaccines.

However this decision has caused controversy in Japan, where researchers claim this is downplaying the severity of the variant. One researcher argued: “because the Lambda variant is relatively resistant to the vaccine-induced [antibodies], it might be possible that this variant is feasible to cause breakthrough infection."

However evidence taken from the US suggests that Lambda is nowhere near as infectious as the Delta variant, which is currently designated a ‘variant of concern’ by the WHO. Although both variants were spread to the US after being first identified elsewhere, Lambda accounts for less than 0.2% of new cases while around 93% of new cases are thought to be caused by Delta.

These findings are backed up by Marie Van Kerkhove of the WHO’s covid-19 response team, who said recently that the Lambda variant does not appear to "take off once it's reported in a country."