The COVID-19 pandemic is in its second year. However, the rapidly mutating SARS-CoV-2 virus is only making life difficult. A recent internal document Centers for Disease Control and Prevention (CDC) has stated that the notorious Delta variant of the coronavirus is as infectious as chickenpox and a lot more transmissible than flu or common cold or SARS.
Titled Improving communications around vaccine breakthrough and vaccine effectiveness, it asserted that the Delta variant—a variant of concern (VOC) that originated in India—can be transmitted even by vaccinated people, and can potentially cause more severe infection than the coronavirus' older strains.
Additionally, the document emphasized that unvaccinated individuals were 10 times more likely to experience serious illness or death than vaccinated people. And the risk of infection among the vaccinated reduced by 3-fold. "Acknowledge the war has changed. Improve public's understanding of breakthrough infections. Improve communications around individual risk among vaccinated," it said.
Lethal Variant of Concern
VOCs have mutations that equip them with lethal transmissibility and immune evasion. Currently, four variants of SARS-CoV-2 have been declared as VOCs by the WHO—Alpha (B.1.1.7- UK), Beta (B.1.351- South Africa), Delta (B.1.617.2- India), and Gamma (P.1- Brazil). The Delta variant emerged in India in late 2020. It is widely believed that the devastating second wave which struck the country in early 2021—leading to extensive loss of lives—was due to this variant.
Also, the Delta variant has become the dominant strain in several countries, sparking fears of more aggressive and devastating waves. According to the latest reports from the WHO, the VOC is driving the fourth wave in the Middle East. Therefore, the warnings and recommendations from the CDC come at a crucial juncture where the Delta variant is dictating the course of the pandemic.
Not Sparing Even the Vaccinated
Reuters stated that the authenticity of the document—which was first reported about by The Washington Post—was verified by the CDC. According to the communication, the Delta variant is single handedly more contagious than other deadly diseases such as MERS, SARS, and Ebola.
It pointed out that in the event of breakthrough infections with Delta variant, the chance of vaccinated individuals being able to transmit the infection is the same as those who are unvaccinated. A breakthrough infection is when a fully vaccinated person tests positive for COVID-19.
In comparison to the Alpha variant, the risk of re-infection with the Delta variant was also said to be higher. However, this is only if the prior infection was 180 days earlier or above. Along with a generally higher viral load associated with the variant, the document also said that there was a 10-fold increase in viral load for the VOC in the breakthrough infections noted in the US. This was in contrast with the Alpha and other lineages.
Citing an outbreak in Barnstable County, Massachusetts, the CDC document pointed out that there was no difference in the Ct values (viral load) in unvaccinated and vaccinated cases. "High viral loads suggest an increased risk of transmission and raised concern that, unlike with other variants, vaccinated people infected with Delta can transmit the virus," said Dr. Rochelle Walensky, director of CDC, according to Reuters.
Precautionary Measures Crucial
Earlier this week, the CDC issued an advisory that sought fully vaccinated individuals to wear masks in situations where there was a likeliness of the virus' spread; a complete reversal of the organization's previous stand. The document also attested to the need for face covering. "Given higher transmissibility and current vaccine coverage, universal masking is essential to reduce transmission of the Delta variant," it read.
Talking to Reuters, Dr. Carlo Federico Perno, head of microbiology and immunology diagnostics at Bambino Gesù Hospital, Italy, averred, "The main thing that does change (because of Delta) is that masks will still be used and that in countries where this requirement has been lifted, it will have to be re-introduced.
Importantly, the communication stressed on the role of Nonpharmaceutical Interventions (NPIs) "NPIs are essential to prevent continued spread with current vaccine coverage," it said. Despite efforts to ramp up inoculation, nearly a third of adults in the US are yet to receive their first dose. Vaccine hesitancy has served as a contributor to this. Recently, US President Joe Biden suggested that local governments incentivize vaccination.
As of 30 July 2021, India has achieved a cumulative COVID vaccine coverage of 46 crores. Of this, fully vaccinated individuals amount to around 10 percent. While several states are easing lockdown restrictions, some states are witnessing a massive resurgence of the virus. Kerala, which managed the pandemic effectively last year, is currently the largest contributor to daily cases in the country.