ECONOMYNEXT – Sinopharm vaccine have the least antibody response after three months compare to other vaccines, the latest antibody response for vaccines study done by a Sri Lankan research team shows.
An antibody response research done by the Allergy Immunology and Cell Biology unit of University of Sri Jayewardenepura has shown that the antibody response was seen highest in the Moderna vaccine followed by Sputnik V, AstraZeneca, Sputink V light (first dose then) and then Sinopharm.
“The ACE2 blocking antibody levels were highest to lowest was Moderna > Sputnik V/ Oxford AstraZeneca (had equal levels)> first dose of Sputnik V (Sputnik light) > Sinopharm,” the study said.
Sinopharm is the most widely used vaccine in Sri Lanka which is generally believed to have contributed to lower levels of hospitalization and deaths, but its usefulness declines over time faster than others used in the country.
In Sri Lanka recipients of all vaccines are being urged to get the Pfizer as a third booster which the government has made available.
ACE2 is a protein on the surface of many cell types. It is an enzyme that generates small proteins – by cutting up the larger protein angiotensinogen – that then go on to regulate functions in the cell.
It is present in many cell types and tissues including the lungs, heart, blood vessels, kidneys, liver and gastrointestinal tract. It is present in epithelial cells, which line certain tissues and create protective barriers.
ACE2 is a vital element in a biochemical pathway that is critical to regulating processes such as blood pressure, wound healing and inflammation, called the renin-angiotensin-aldosterone system (RAAS) pathway and it helps modulate the many activities of a protein called angiotensin II (ANG II) that increases blood pressure and inflammation, increasing damage to blood vessel linings and various types of tissue injury.
ACE2 converts ANG II to other molecules that counteract the effects of ANG II.
Of greatest relevance to COVID-19, ANG II can increase inflammation and the death of cells in the alveoli which are critical for bringing oxygen into the body; these harmful effects of ANG II are reduced by ACE2.
When the SARS-CoV-2 virus binds to ACE2, it prevents ACE2 from performing its normal function to regulate ANG II signaling. Thus, ACE2 action is “inhibited,” removing the brakes from ANG II signaling and making more ANG II available to injure tissues.
This “decreased braking” likely contributes to injury, especially to the lungs and heart, in COVID-19 patients.
“We assessed antibody responses 3 months’ post-vaccination in those who received mRNA-1273 (n=225), Sputnik V (n=128) or the first dose of Gam-COVID-Vac (n=184) and compared the results with previously reported data of Sinopharm and AZD1222 vaccines” the research team said.
Of that 99.5 percent of Moderna, 94 percent of Oxford AstraZeneca (AZD1222) or Sputnik V, 72 percent to 76 percent of (Sputnik light) Gam-COVID-Vac (first dose) and 38.1 percent to 68.3 percent of Sinopharm vaccines had ACE2 blocking antibodies above the positive threshold”
Also read; AstraZeneca second shot at 12-weeks gives same antibody levels as 4-weeks: Sri Lanka study
The study showed that all Moderna recipients had antibodies above the positive threshold to the Alpha variant (B.1.1.7), Beta variant (B.1.351.1) and 80percent positivity rate for Delta variant (B.1.617.2).
Positivity rates of Sputnik V vaccines for Wild Types and variants, were higher than AstraZeneca vaccine, while Sinopharm vaccine had the lowest positivity rates (<16.7percent).
Director of Allergy Immunology and Cell Biology unit of USJ, Chandima Jeewandara said these differences in the persistence of immunity to different vaccines is likely to have significant implications in breakthrough infection rates, hospitalization and severe disease in different vaccine recipients.
He said, Sri Lanka should consider the factors such as the majority of the population is vaccinated with Sinopharm, already witnessing signs that vaccines lose their potency over time (Waning of Immunity), O effect / Variants and availability of booster vaccines.
“Vaccines will continue to prevent severe disease caused by the variants — but to what extent is not yet clear. We are already witnessing that infections have been uncoupled from deaths in Sri Lanka” Jeewandara said in his twitter.com feed.
“If you are Sinopharm vaccinated – get your booster three months after completing your primary COVID-19 vaccination series”
“If you have recovered from COVID 19 after full vaccination (hybrid Immunity): you may delay the booster shot for 6 months, but it is best that you seek an opinion from your physician (severity of your illness, age, comorbidities and your medicines will affect the immunogenicity)”
Sinopharm is the most used vaccine in country and the health officials have vaccinated 11,960,092 with the first dose while 10,972,235 with both first and second doses.
The AstraZeneca vaccine’s first dose has been administered to 1,479,631 and 1,418,593 has been given both first and second doses.
Some 159,110 has received the first dose from the Sputnik V vaccine and 155,812 has received both doses.
The first dose of Moderna Vaccine has been administered to804,801 while 787,361 has been given both doses.
So far 2,058,791 has received the booster dose from Pfizer vaccine. (Colombo/ Dec 19/2021)