The Delta variant of the coronavirus, first detected in India, has now spread to at least 74 countries, according to reports aggregated by the World Health Organization, threatening a massive resurgence of the pandemic as reopenings worldwide continue apace.
The variant was first sampled last October, and is most likely responsible for the 35-fold increase in cases reported in India from February to May, reaching a peak of more than 390,000 cases each day, with a corresponding 45-fold increase in daily deaths, topping out at 4,500 reported fatalities. To date, India has suffered 29.6 million known coronavirus cases and at least 377,000 officially counted deaths, a number widely understood to be far lower than the actual death toll.
There have been more than 177 million cases of the pandemic worldwide, and at least 3.8 million deaths.
Now, the Delta variant is surging throughout the United Kingdom. Since mid-May, new cases in the country have more than tripled to nearly 7,500 a day, of which at least 90 percent are a result of the Delta variant, according to Public Health England (PHE).
In the United States, there is a concern that a similar trend will occur. The mutation now accounts for about 10 percent of new cases, with former Food and Drug Administration Commissioner Scott Gottlieb warning on CBS that those with the Delta variant “have higher viral loads” and “shed more of the virus.” According to the US Centers for Disease Control and Prevention, the Delta is the third most common variant of coronavirus in the United States, after the Alpha (UK) and Gamma (Brazil) variants, and is the second most common variant in Health and Human Services regions 2, 7 and 8, encompassing Colorado, Iowa, Kansas, Missouri, Montana, Nebraska, New Jersey, New York, North Dakota, Puerto Rico, South Dakota, Utah, the Virgin Islands and Wyoming.
Moreover, the number of cases caused by the Delta variant have more than tripled in the past two weeks, a trend which indicates it will likely become dominant in the US by the end of June if it continues to spread at the same rate.
Cases have also risen in Indonesia by 37 percent over the last seven days as a result of the new mutation. Further outbreaks have been detected in China, South Asia, the Pacific rim and across Africa.
As a result of such outbreaks, the decline in daily cases worldwide has begun to slow. According to the World Health Organization, while the number of new cases has declined for seven weeks in a row largely thanks to vaccination efforts, the global decline is concealing a growth in cases caused by the Delta variant, especially in regions with low rates of vaccination. “That means,” as stated by WHO Director-General Dr. Tedros Adhanom Ghebreyesus, “the risks have increased for people who are not protected, which is most of the world’s population.”
The risks are manifold. A study by PHE of Delta variant cases in England found that it causes 2.61 times more hospitalizations than the Alpha variant, and causes about 4.1 times more hospitalizations than the original variant. The Delta variant is also much more transmissible, somewhere between 50 to 60 percent more infectious than the Alpha variant, thus more than twice as infectious as the wild coronavirus.
The ability of the Delta variant to spread has been quantified by a variety of researchers and public health officials. In Australia, Victoria’s Deputy Chief Health Officer Allen Cheng noted that the reproduction number (R0) of the Delta variant is likely about 5, meaning that one person infected with the virus would spread it to five others if uncontrolled. Disease modelers at Imperial College London estimate the R0 value for the Delta variant could be as high as 8.
In comparison, the R0 for the original coronavirus was estimated to be between 2.0 and 2.5. Put another way, if 10 people were infected with the original variant, about 1,520 people would be infected after four weeks if there were no measures to contain the virus. Ten people infected with the Delta variant, in contrast, would infect 4 million people over that same period. Such high reproduction rates are why viruses like measles are so dangerous and why so much effort is spent to develop and distribute vaccines.
Of course, viruses do not in general spread so quickly, mitigated by public health measures, vaccines and our own immune systems. The coronavirus vaccines, for example, have been shown to be largely effective at preventing serious illness and death caused by the Delta variant.
The much higher transmissibility, however, means that more people will have to become vaccinated to stop the spread of the variant if it becomes dominant, which it is currently poised to do. While earlier estimates of the herd immunity threshold called for at least 70 percent of the world’s population to become vaccinated, the Delta variant implies a needed vaccination rate of 80-85 percent, a difference of between about 800 million and 1.2 billion humans.
Moreover, vaccines have only been effective against the Delta variant after the full vaccine regimen has been completed. Protection against infection after just a single dose of the Pfizer vaccine, for example, is at best 36 percent effective at preventing a serious infection, according to figures from PHE. As a result, there have been thousands of patients in the UK that have so far contracted the Delta variant after receiving only their first vaccine dose.
Such infections present an added danger to the British and world population: while the Delta variant is not itself immune to the vaccine, its ability to infect partially vaccinated individuals means there is a distinct possibility that it will evolve to be completely immune to the vaccine. If such an “escape” variant were to develop, it would reignite the pandemic with an even greater virulence than ever.
The solution to such a potential catastrophe is both to accelerate the distribution of vaccines worldwide and to maintain and expand comprehensive public health measures. As Dr. Mike Ryan, WHO Executive Director noted on Monday, “I would just maybe remind us all that, I think, in 2020, we spent nearly $2 trillion. I think that was around $1,981 billion in defence spending around the world. $16 billion [needed by WHO to vaccinate the world] represents less than 1 percent of one year’s spending on military defence around the world. Surely, we can afford 1 percent of that to save lives and bring this pandemic to an end.”
And as Dr. Tedros noted, while “high vaccination rates have helped cases and deaths from COVID-19 to near record lows” in the world’s wealthier countries, most “continue to rely solely on the public health and social measures,” including lockdowns, masking, testing and contact tracing, “that have been the backbone of the response to date.”
Such measures, however, are being abandoned wholesale. In the United States, for example, with the administration of Democrat Joe Biden leading the charge, mask mandates have been largely dropped and schools and workplaces are slated to fully reopen by the fall. Little thought is given to the 600,000 lives that have been lost in that country alone, or to the further heights of mass death to come as virtually all public health measures are discarded even as the most dangerous coronavirus variant to date continues to surge.