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Phase-1 trial: Adenovirus COVID-19 vaccine found safe, induces immune responses

Trial was carried out on 108 participants aged 18-60 in Wuhan

A phase-1 trial using a single dose of a vaccine (Ad5-nCoV) that uses a recombinant adenovirus type-5 vector that carries the genetic material that codes for spike glycoprotein of novel coronavirus was found to be safe, well-tolerated and able to generate immune responses against the virus. The adenovirus is a weakened common cold virus.

The trial was carried out on 108 participants aged 18-60 years in Wuhan, China, and had 36 participants each in the low, middle and high-dose groups.

The trial did not involve randomisation of participants and did not have a control arm. The results are based on short duration of follow-up. The results were published in the journal The Lancet.

Safety of the vaccine

The most common adverse reaction was pain at the injection site (58 participants or 54%), fever (50 participants), fatigue (47 individuals), headache (42 participants) and muscle pain (18 participants). Most adverse reactions reported were mild or moderate in severity. One participant who was given the higher dose vaccine reported severe fever, along with severe symptoms of fatigue, shortness of breath and muscle pain. However, these adverse reactions persisted for less than 48 hours. No serious adverse event was noted within 28 days post-vaccination.

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“As it was a first-in-human study of the adenovirus type-5 vectored COVID-19 vaccine, it was not designed to measure the vaccine efficacy,” they write. But they note that in animal studies, seven out of eight ferrets were protected when challenged by the virus 21 days after immunisation with the vaccine.

Immune responses

The vaccine was found to elicit neutralising antibodies, which peaked at day 28 post-vaccination, while rapid specific T-cell responses peaked at day 14 after vaccination. The antibody response to the vaccine in the high-dose group was slightly greater than that in the middle-dose and low-dose groups.

After 28 days, most participants had a four-fold increase in binding antibodies (35/36, 97% low-dose group; 34/36 (94%) middle-dose group, and 36/36, 100% in high-dose group). Meanwhile, 18 (50%) participants in the low-dose group, 18 (50%) in the middle-dose group, and 27 (75%) in the high-dose group showed neutralising antibodies against the virus.

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The vaccine also stimulated a rapid T cell response in the majority of volunteers, which was greater in those given the higher- and middle-doses of the vaccine, with levels peaking at 14 days after vaccination. About 83% (30 of 36) of low-dose participants, 97% (35 of 36) of middle-dose participants and 97% (35 of 36) of high-dose participants developed T cell responses at 14 days.

But 28 days after vaccination, the majority of recipients showed either a positive T cell response or had detectable neutralising antibodies against SARS-CoV-2 (low-dose group 28/36, 78%; middle-dose group 33/36, 92%; high-dose group 36/36, 100%).


The pre-existing immunity to adenovirus type-5 vector used in the vaccine, regardless of the vaccine doses, could reduce the immune responses (both neutralising antibodies and T-cell response) to the virus and also lower the peak of the responses, particularly for neutralising antibodies immunity. The high pre-existing immunity might also have a negative effect on the persistence of the vaccine-elicited immune responses, they write. Recipients aged 45-60 years seemed to have lower seroconversion of neutralising antibody, compared with the younger recipients.

In the study, 44-56% of participants had high pre-existing immunity to adenovirus type-5, and had a less positive neutralising antibody and T-cell response to the vaccine, they note.

Only five (25%) participants of 20 in the low-dose group, seven (37%) participants of 19 in the middle dose group, and ten (63%) participants of 16 in the high dose group, who had high pre-existing immunity to adenovirus type-5, had at least a four-fold increase in neutralising antibody titre at day 28 post-vaccination.

Phase-2 trial

The researchers will be testing the low- and middle-dose vaccine in phase-2 trials. “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.

The phase-2 trial will be a randomised, double-blinded and placebo-controlled trial. The trial has already been initiated in Wuhan to determine if the results can be replicated and to also assess the vaccine for safety up to six months after vaccination. The vaccine will be tested on 500 healthy adults — 250 volunteers will get the middle dose, 125 will get the low dose and 125 will receive a placebo. The trial will include participants aged over 60.R. Prasad : , The Hindu


Rotavirus vaccine to be introduced in Mizoram by July

The vaccination for rotavirus is set to be introduced in the state of Mizoram by July 2019.

Rotavirus, which according to the WHO, is the most common cause of severe diarrhoeal disease in young children throughout the world.

An introductory workshop was held at the Directorate of Health Services, Conference Hall on Monday.

Dr Tushar Rane, chief of Field Office and representative of UNICEF Northeast gave an introduction of the rotavirus vaccine and spoke on how this vaccine has been introduced in other states of India.

The mission director, NHM,Dr Eric Zomawia gave a keynote address where he spoke on the various endeavours and future plans of the Health department while the State Immunization Officer Dr Lalzawmi gave a power-point presentation on the ‘Overview of Universal Immunization programme’.

The rotavirus vaccine is expected to be introduced in the State by June or July 2019 after the completion of state and district level training.

The vaccine will be given in three doses to six week, 10 week and 14 week old infants.

The administration of the vaccine can only be carried out by trained medical experts.

While two states in the Northeast, Assam and Tripura have administered the vaccine, instruction has been received from the Ministry of Health & Family Welfare, Government of India to administer the vaccine in the rest of the north-eastern states.

Rotavirus vaccine will be included in the Routine Immunisation vaccines under the health department of Mizoram.

The virus which is the most common cause of severe diarrhoea is believed to claim the lives of more than 200,000 children each year. More than 80 per cent of children get infected by 5 years of age.

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Diarrhoea caused by Rotavirus is one of the leading causes of severe diarrhoea and death among children less than five years of age. In India, between 80,000 to one lakh children die due to Rotavirus diarrhoea annually while nearly 9 lakh children are admitted to hospital with severe diarrhoea. Another 32.7 lakh children visit the hospital as out patients due to the disease.

The vaccine was being introduced initially in four States — Andhra Pradesh, Haryana, Himachal Pradesh and Odisha — and would be expanded to the entire country in a phased manner, Mr. Nadda said. “Adding this life-saving vaccine to our immunisation programme will not only improve the health of our children but also reduce hospitalisation and other conditions associated with diarrhoea due to Rotavirus such as malnutrition, delayed physical and mental development among children. Reduced hospitalisation lower the economic burden on the family and the health cost burden on the country,” the Minister added. The Rotavirus vaccine was developed indigenously, under a public-private partnership between the Ministry of Science Technology and the Health Ministry.

The Rotavac is in addition to three new vaccines that have been introduced in India’s Universal Immunisation Programme (UIP) including Inactivated Polio Vaccine (IPV), Measles, Rubella (MR) vaccine, and Adult Japanese Encephalitis (JE) vaccine.

With these new vaccines, India’s UIP will provide free vaccines against 12 life threatening diseases, to 27 million children annually, the largest birth cohort in the world.