As the world started to take a breath, with the vaccination efforts accelerating driving optimism that the coronavirus pandemic could recede to the background, a new threat emerged, the Delta variant.
Delta variant is a highly contagious coronavirus mutation, it was first discovered in India before it rapidly spread across the globe. Delta became the dominant strain in the US, UK, and several other countries.
The World Health Organization (WHO) has called this version of the virus “the fastest and fittest.” In mid-June, the CDC labelled Delta as “a variant of concern.”
In the United States hospitalization rates have been on the rise. In New York, 70% of the eligible population have received at least one dose of vaccine.
So far, people who have not been fully vaccinated against COVID-19 are most at risk. According to Yale University, people who are fully vaccinated against the coronavirus appear to have protection against Delta.
However, in some communities in the US, especially in the southern states there is a disproportionate number of unvaccinated people, the number of cases is on the rise even as some other states are lifting restrictions because their cases are going down.
According to the latest figures, the Delta variant is spreading faster in US counties where less than 30% of residents have been fully vaccinated, compared to the counties with vaccination rates above that threshold.
Africa in the crosshairs of Delta
Several scientists fear that the new variant will have a major impact in Africa and other places where vaccination efforts have been slow. As several countries across the continent have vaccinated less than 5% of the population, thus they may embrace a devastating impact.
Although several African countries have limited detection, there are several indicators that the Delta variant cases are on the rise. This is apparent in the Democratic Republic of the Congo, where an outbreak in the capital city of Kinshasa has filled hospitals. The variant has also been detected in Malawi, Uganda and South Africa.
Recently, Nature Magazine reported that East African countries with close ties to India are at higher risk of Delta variant cases, according to Tulio de Oliveira, a bioinformatician and director of the KwaZulu-Natal Research and Innovation Sequencing Platform in Durban, South Africa.
Oliveira explained that in South Africa Delta variant cases have been detected in shipping crews at commercial ports, with no signs yet of spread in the general community.
The country which in its third wave of the pandemic, mainly from the Beta variant (generally known as the South African Variant), might suffer from limited impact from Delta.
Similarly, many scientists believe that Brazil has a low risk of Delta, as the dominant strain there is the Gamma variant (the Brazilian Variant).
The next big question that rose is how does the coronavirus vaccine work against the Delta variant? Several studies have been conducting and many others on the way to analyze the degree of protection that current vaccines provide.
According to Dr Miriam Smith, chief of infectious disease at Long Island Jewish Forest Hills Teaching Hospital in Queens, New York City, the unvaccinated population remain at higher risk for infection.
Similarly, CDC Director Dr Rochelle WalenskyTrusted Source issued a warning on this potential surge in early July.
In a press briefing, she said preliminary data suggested that 99.5% of the people who died from COVID-19 since January were unvaccinated.
“We know that the delta variant… is currently surging in pockets of the country with low vaccination rates,” she said.
This goes in line with a study that was conducted in the UK, which found that the delta variant is twice as likely to lead to hospitalization, and both the AstraZeneca-Oxford and Pfizer-BioNTech COVID-19 vaccines being effective in reducing this risk.
Healthline reported that those three vaccines provide protection against the delta variant, according to Dr Theodore Strange, the interim chair of medicine at Staten Island University Hospital in New York.
In many studies, those three vaccines are proven to be effective in varying degrees against the original variant of the coronavirus.
However, since the delta variant emerged, scientists have been trying to establish whether these vaccines are as effective against it.
The Pfizer-BioNTech COVID-19 vaccine
Due to limited research so far, trying to determine the effectiveness of each vaccine against the delta variant remains a challenge. However, there have been promising results from multiple studies.
According to an analysis carried out by Public Health England, two doses of the Pfizer-BioNTech vaccine appeared to be about 88% effective against symptomatic disease and 96% effective against hospitalization with the delta variant.
The same study suggested that the vaccine was approximately 80% effective against preventing infection from the delta variant. Scientists came to this conclusion after analyzing 14,019 people with an infection, 166 of whom were hospitalized, in England.
Vaccines had a protective effect against infections with delta and hospital cases were milder, the study found.
Public Health England also shared real-world data in May that solidified the importance of having a second dose of the COVID-19 vaccine. The analysis suggested that a single dose of the Pfizer-BioNTech vaccine offered only about 33% protection against symptomatic disease.
This was a reduction from the previous 50% effectiveness estimated against the alpha variant.
The study also found that the Pfizer-BioNTech vaccine was 88% effective against the delta variant 2 weeks after the second dose.
A reportTrusted Source published in the journal Nature reflected the findings that a single shot of a two-dose vaccine such as Pfizer-BioNTech or AstraZeneca provided “barely” any protection.
However, researchers also reported that people who had received two doses of a vaccine had significantly more protection against infection with the delta variant, with researchers estimating a level of 95 percent effectiveness.
The study also found that the delta variant was less sensitive to “sera from naturally immunized individuals,” meaning people who had a prior infection may not be protected against reinfection with the delta variant.
A study in Canada, meanwhile, found that two doses of a COVID-19 vaccine worked just as well against the delta variant as it did with alpha. It has not yet been peer-reviewed.
The study suggested the Pfizer-BioNTech vaccine was around 87 percent effective 14 days after two doses.
A study in ScotlandTrusted Source found similar results. The Pfizer-BioNTech vaccine, researchers concluded, offered “very good” protection against the delta variant and demonstrated 79 percent effectiveness 14 days after receiving the second dose.
A study in Israel was more of an outlier and found that the Pfizer-BioNTech vaccine did not offer as high protection as previously estimated. The study suggested the vaccine was about 64 percent effective against preventing infection with the delta variant and 64 percent effective against symptomatic illness after two doses.
But scientists have pointed out that the full data has not yet been released, and it may have included asymptomatic infections picked up by Israel’s surveillance program.
The Indian Council of Medical Research has undertaken a study to understand the protective immune response to infection with Delta variants and the effects of vaccines on this response in light of the limited amount of research available.
The researchers aimed to evaluate the vaccine-induced humoral immune response in individuals who had received the Covishield vaccine, investigating: 1) those receiving one dose, 2) receiving two doses, 3) COVID-19 convalescents with one dose of the vaccine, 4) COVID-19 convalescents with two doses of the vaccine as well as 5) breakthrough COVID-19 cases.
However, investigations of convalescent patients who had recovered from COVID-19 and had received either one or two doses of the vaccine had illustrated higher neutralizing antibody titers compared to those who were given the vaccine but did not suffer from the infection.
This led to the conclusion that even one dose of the vaccine for these convalescent participants was enough to provide sufficient protection both against re-infection as well as against any emerging novel variants.