A new subvariant of the Omicron variant of SARS-CoV-2, the virus that causes COVID-19, has emerged and is raising concerns globally. Dubbed ‘Pirola’, this subvariant was first detected in Denmark in late July 2023 and has since spread to several other countries.
Pirola is notable for having over 30 mutations distinguishing it from previous Omicron subvariants. Some of these mutations are located in key areas like the spike protein and are thought to make Pirola more transmissible and better able to evade immune defenses.
Early Evidence Suggests Increased Transmissibility
While Pirola’s prevalence remains low globally, early evidence indicates it is increasing in frequency relative to other Omicron subvariants, suggesting it is more transmissible. For example, in Denmark Pirola now accounts for around 2% of sequenced cases, up from 0.8% a few weeks prior. Similar upticks have been reported in the UK, US, Canada, and Israel.
More research is needed to firmly establish Pirola’s growth advantage. However, the parallels with early dynamics seen in variants like Alpha and Delta, which proved highly transmissible, are concerning. Experts are closely monitoring the subvariant’s spread.
Potential for Immune Evasion
A key worry is that Pirola’s mutations may enable it to partially evade existing immune defenses. This could increase the risk of reinfection in those previously infected or vaccinated.
Early lab studies suggest antibodies from vaccines and previous infection are less effective at neutralizing Pirola compared to other Omicron subvariants. Fortunately, protection still seems robust, especially in those that were vaccinated and boosted.
However, there are concerns Pirola may erode some of the population-level immunity built up globally. More data is needed regarding real-world vaccine effectiveness against this subvariant.
Unclear Severity Profile
The severity of infections caused by Pirola remains unclear and will require more time to discern. Thus far, hospitalization rates where Pirola is circulating do not appear substantially changed. This suggests its intrinsic virulence is unlikely to differ dramatically from existing subvariants.
However, if Pirola is significantly more transmissible and capable of reinfecting individuals, the overall burden of severe disease at a population level could still be greater. Experts caution the public health implications will depend on both the subvariant’s transmissibility and disease severity.
Ongoing Monitoring Critical
The WHO has designated Pirola as a ‘Variant of Interest’ due its mutation profile and preliminary signs of increased transmissibility. While not an immediate cause for alarm, it signals Pirola warrants very close monitoring.
Staying vigilant for new concerning variants and quickly assessing their risks remains critical. The spread of Pirola emphasizes the pandemic is not over and the importance of genomic surveillance, vaccines, treatments, and other measures to maintain hard-fought gains against COVID-19.
Experts advise the public should keep up-to-date with vaccinations, exercise caution in high-risk settings, and follow local public health recommendations. While Pirola’s implications are still unfolding, these common-sense measures will help mitigate risk. Continued research and real-world data will provide greater clarity on whether Pirola poses a significant new threat.
