Delta Variant is ‘More Transmissible Than Ebola’, and Vaccinated People May also be Highly Contagious
Samples of SARS-CoV2 variants obtained and monitored by WHO, in collaboration with partners, expert networks, national authorities, institutions and researchers.

The war against COVID-19 has changed with the emergence of the highly transmissible and deadly Delta variant, said an internal US Centers for Disease Control and Prevention (CDC) slide presentation.

The document, which has not yet been released, was obtained by the Washington Post and calls for a new and more aggressive masking and vaccination strategy in the US to combat the spread of the Delta variant.

Most alarmingly, it warns that people with breakthrough infections, which are cases that occur despite full vaccination, may be as contagious as unvaccinated people. 

“We are dealing with a different virus now,” Dr Anthony Fauci, Director of the National Institute of Allergy and Infectious Diseases and the Chief Medical Advisor to President Joe Biden, told NPR on Tuesday.

“This is not the original virus that we were dealing with. This has different capabilities [and is] much more efficient in transmitting from person to person,” he said.

Delta variant more transmissible than Ebola, common cold and smallpox

The Delta variant (B.1.617.2), first identified in India in October 2020, has been described by WHO officials as the “fastest and fittest” variant. The variant has been sweeping across the world, now reported in 132 countries

The newest variant of concern is “considerably more transmissible” than previous variants and has a viral load approximately a thousand times higher than the original virus, said Fauci in a closed-door meeting on 29 July with Members of Congress. 

Estimates suggest that an individual infected with the Delta variant will pass the disease on to between five and nine other people, while the original virus would be passed on to two to three people. 

This indicates that the Delta variant is more transmissible than MERS, SARS, Ebola, the common cold, the seasonal flu, and smallpox. The variant spreads as easily as chickenpox, according to the federal health document. 

Delta variant is more transmissible than MERS and SARS, Ebola, the common cold, the seasonal flu and 1918 flu, and smallpox, according to the CDC.

“I think people need to understand that we’re not crying wolf here. This is serious,” Dr Rochelle Walensky, Director of the CDC, told CNN. “It’s one of the most transmissible viruses we know about. Measles, chickenpox, this – they’re all up there.”

The data presented in the internal document was “sobering,” said Walensky. 

The Delta variant may also cause more severe disease than previous strains of SARS-CoV2. Studies conducted in Canada and Scotland found that people infected with the variant are more likely to be hospitalized, while a study from Singapore indicated that patients are more likely to require oxygen, admission into an intensive care unit, or develop pneumonia.  

More drastic action is needed to deal with Delta threat

The CDC’s new masking guidelines for vaccinated people, which were introduced on Tuesday, were based on the data presented in the document. 

“To reduce the risk of being infected with the Delta variant and possibly spreading it to others, wear a mask indoors in public if you are in an area of substantial or high transmission,” said the updated guidelines.

The new guidelines, however, didn’t go far enough in the context of the threat posed by the Delta variant.

“Given higher transmissibility and current vaccine coverage, universal masking is essential,” said the document. 

“The measures we need to get this under control, they’re extreme,” said Walensky. 

“Nonpharmaceutical interventions are essential to prevent continued spread with current vaccine coverage,” the document said. 

Along with universal masking and community mitigation strategies, the document recommends a vaccine mandate for healthcare personnel to protect vulnerable populations.

The CDC also faces the daunting communication challenge of emphasizing the efficacy of the COVID vaccines in preventing severe illness and death, while improving the public’s understanding of breakthrough infections and acknowledging that vaccinated people are transmitting the virus.

Immunized people as vectors for SARS-CoV2 virus

Although unvaccinated people account for the bulk of virus transmission, vaccinated people can also be vectors for the SARS-CoV2 virus, found a new CDC report released on Friday.

The report was based on an outbreak of 469 cases of COVID in Barnstable County, Massachusetts, following a series of large public gatherings in early to mid-July. Approximately 74% of cases occurred in fully vaccinated people and 89% of the cases were caused by the Delta variant.

Among those with a breakthrough infection, 79% reported symptoms, the most common being cough, headache, sore throat, muscle aches, and fever.

The report concluded that, as population-level vaccination coverage increases, vaccinated people are likely to represent a larger proportion of COVID cases. Breakthrough infections are also expected to occur with greater frequency among groups at risk of primary vaccine failure, such as those with compromised immune systems or those over the age of 60. 

The authors suggested that even areas without high COVID transmission should expand prevention strategies by requiring masks indoors and limiting capacity at gatherings.

Vaccinated people may be as contagious as unvaccinated people

Inoculated people infected with the Delta variant carry tremendous amounts of the virus in the nose and throat, said CDC officials. The vaccine-induced antibodies largely remain in the blood, so vaccinated individuals won’t have local immunity in the nose or throat. 

This means that they will be able to transmit the virus to others while they are infected and contagious. 

People with breakthrough infections may be as contagious as unvaccinated people, found the internal CDC document.

There are currently 35,000 symptomatic infections reported per week among 162 million vaccinated Americans. 

“Vaccines prevent more than 90% of severe disease, but may be less effective at preventing infection or transmission,” said the internal CDC slide presentation. “Therefore, [there will likely be] more breakthrough and more community spread despite vaccination.”

This, however, doesn’t undermine the efficacy of vaccines. The risk of severe disease or death is reduced ten-fold or greater in vaccinated individuals and the risk of infection is reduced three-fold.

Infections, hospitalizations, and deaths on the rise in the US

Infections in the US have increased 145% in the past two weeks, accompanied by rising rates of hospitalizations and deaths, particularly in areas with low vaccination rates. 

According to CDC estimates, over 80% of recent COVID cases in the US have been caused by the Delta variant.

Cases in all but one state have risen in the past seven days.

The current number of new COVID cases is higher than the peak reported last summer and hospitalizations have reached the same level as this time last year, before vaccines were available. Hospitalizations are much more common now among patients aged 30 to 39 years old, compared to those over the age of 70. 

“This sudden turn of events threatens to undermine the significant progress we have made this year to overcome the pandemic,” said Representative James E. Clyburn, Congressperson and Chair of the Select Subcommittee on the Coronavirus Crisis, at a briefing with CDC officials on Thursday. 

“Getting vaccinated remains the most effective way to save lives and stop the spread of the Delta variant,” said Clyburn.

In a recent attempt to revive vaccine efforts, US President Joe Biden will require all federal workers and members of the military to either get vaccinated or face regular testing, social distancing, and mask wearing. 

He urged companies and local governments to follow his lead. “This is a pandemic of the unvaccinated,” said Biden at a press conference on Thursday. “People are dying and will die who don’t have to die. If you’re out there unvaccinated, you don’t have to die. Read the news.”

Some 90 million Americans are eligible for a vaccine but have not yet gotten one. 

“With incentives and mandates, we can make a huge difference and save a lot of lives,” said Biden, who also urged states to offer US$100 to anyone willing to get a jab. 

This move, however, has been criticized by some as rewarding the unvaccinated.

Image Credits: WHO, CDC.

Combat the infodemic in health information and support health policy reporting from the global South. Our growing network of journalists in Africa, Asia, Geneva and New York connect the dots between regional realities and the big global debates, with evidence-based, open access news and analysis. To make a personal or organisational contribution click here on PayPal.