Friday, 05 June, 2020

CanSino Biologics trigger immune response: Chinese researchers

Pair of studies showed vaccine prevented coronavirus infection in monkeys; produced antibodies Harvard Medical School monkey trials show promising COVID-19 vaccine results
Gustavo Carr | 24 May, 2020, 00:53

The scientists said their vaccine produces virus-specific antibodies and immune cells in 14 days, but cautioned that more research is needed to determine whether it actually protects against the infection.

"These results represent an important milestone", the lead researcher on the study, Professor Wei Chen, said.

In a May 15 study published on the preprint server bioRxiv, the researchers found that a single dose of ShaCoVacc resulted in an "immediate and potential immune response" against SARS-CoV-2, the virus that causes COVID-19, "in contrast to an inactivated vaccine which required at least two or three doses of injections".

"These results should be interpreted cautiously".

"The challenges in the development of a COVD-19 vaccine are unprecedented, and the ability to trigger these immune responses does not necessarily indicate that the vaccine will protect humans from COVID-19", Chen said. He also warned that there is still a long way to go before this vaccine becomes available. "We selected doses for the phase-2 study mainly on the basis of the safety profile of the candidate vaccines shown in the participants within seven days and 14 days post-vaccination", they note.

Promising results from the completed first human trial China's Ad5 coronavirus vaccine place it at the front of the global race for a shot, though only by a slim margin, an expert told DailyMail.com. These cells then produce the spike protein and travel to the lymph nodes where the immune system makes antibodies that will recognize that spike protein and ward off the coronavirus.

Participants were enrolled from one site in Wuhan, China, and assigned to receive either a single intramuscular injection of the new vaccine at a low dose of 5 × 1010 viral particles per 0.5 milliliters, a middle dose of 1×1011 viral particles per 1.0 ml. or a high dose of 1.5 x 1011 viral particles per 1.5 ml. The vaccine produced neutralising antibodies and a response mediated by the immune system's T-cells against the novel coronavirus, SARS-CoV-2.

In addition, the researchers reported to have tested three doses and said that the highest dose seemed to be the most effective. The antibody response to the vaccine in the high-dose group was slightly greater than that in the middle-dose and low-dose groups.

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More than 80 percent did have some side effects, but these were mostly mild or moderate, like muscle aches, fever and pain. However these effects lasted no more than 48 hours.

All dose levels of the vaccine triggered some immune response - antibodies that bind to the coronavirus but do not necessary attack it - within two weeks of the vaccination. An open-label trial of 108 healthy adults showed good results after 28 days.

Meanwhile, the Ad5-nCoV vaccine also simulated a rapid T cell response in the majority of volunteers. The vaccine elicited a four-fold increase in binding antibodies to the spike protein's receptor-binding domain in 94%-100% of participants and a four-fold increase in antibodies to live virus in 50%-75%.

The primary aim of the trial was safety and the vaccine's ability to give an immune response. "In these two studies, we demonstrate in rhesus macaques that prototype vaccines protected against SARS-CoV-2 infection and that SARS-CoV-2 infection protected against re-exposure".

The study's authors also noted that their research is limited because of its small sample size and short duration, and it also lacked a control group.

The study, conducted in Wuhan, China, by the Beijing Institute of Biotechnology tested different doses of the vaccine in 108 healthy adults who did not have the coronavirus.

Limitations to the study, Chen and colleagues said, include that it was not created to measure vaccine efficacy, and that no participants were older than age 60, with only 16% of participants older than age 50.