British scientists at the NIHR Oxford Biomedical Research Centre had previously used the glycoprotein spike on the surface of coronavirus—which allows them to anchor at a target cell—to produce a chimpanzee adenovirus—vectored vaccine against the Middle East respiratory syndrome coronavirus (MERS-CoV) They had called it ChAdOx1 MERS and represented many hours of study, research and hard laboratory work that would have hardly ever been funded by a private company—often only myopically seeking quick profits in detriment of the larger public good. When the Chinese authorities published the genome of the SARS-CoV-2, the Oxford scientists immediately started working on their template with messenger RNA.

The Oxford team partnered with other institutions in the United Kingdom and eventually got financial support from Astra Zeneca, a Big Pharma conglomerate. The ChAdOx1 nCoV-19 vaccine uses a replication-deficient simian adenovirus vector ChAdOx1 that contains the full-length structural surface glycoprotein of SARS-CoV-2 with a tissue plasminogen activator leader sequence. They had observed that one single dose of that vaccine had induced good humoral and cellular immune responses in monkeys; after high-dose vaccine challenges, there was a notable protection against the lower respiratory infection, a hallmark of the disease. They set up a combined phase 1 and 2 single-blind, randomized controlled trial, comparing it with a Meningococcal group A,C, W-135 and Y conjugate vaccine.

They recruited healthy adult participants aged 18-45 years old, excluding all those volunteers that had positive COVID-19 tests, had symptoms of acute respiratory distress, or were exposed to the disease like health care workers or first responders. The participants were randomly assigned to receive either the ChAdOx1 nCoV-19 vaccine or the meningococcal vaccine—they used an active vaccine because the lack of symptoms from normal saline injections could eventually “unblind” the controls. The participants were divided into four major groups:

  1. Group I: they had intensive early follow-up visits the vaccine’s safety and immunogenicity.
  2. Group II: they had higher blood volumes of humoral and cellular immunogenicity assessment than group 4.
  3. Group III: it consisted of only 10 participants that received a booster shot 28 days after the first injection.
  4. Group IV: participants that had a serum sample drawn for humoral immunology assessments only.

The median age of participants was 35 years old, 49.8% (536) were female and 50.2% (541) were male; the majority (9 or 90.9%) were white. Some received prophylactic paracetamol and some others did not; 328 (67%) of participants in the vaccine group and 180 (38%) of participants in the control group reported pain after the injection. The most reported systemic reactions were fatigue and headache. “In the ChAdOx1 nCoV-19 group, antibodies against SARS-CoV-2 spike protein peaked by day 28 (median 157 ELISA units EU) and remained elevated to day 56 (119 EU) in participants who received only one dose, and increased to a median of 639 EU (360-792) at day 56 in the ten participants that received a booster dose)”

Researchers concluded that one single dose of the ChAdOx1 nCoV-19 was safe and well tolerated, without any major reactions. A single dose of it produced an increase in the spike-specific antibodies by day 28 and the neutralizing antibodies in all the participants after a booster dose. Some studies showed that neutralizing antibodies in the dawn of the disease protected the rhesus macaque monkeys. Antibodies capable of neutralizing live SARS-CoV-2 were induced by day 28 and after a booster dose. T-Cell responses—considered essential for the ultimate defeat of the virus—were evident by day 7 after the dosage and peaked at Day 14. However, the booster dosages did not elicit a similar immunological response.

The researchers admitted that this study had serious limitations, foremost of all that it involved all healthy individuals that were not fully representative of their society. They designed Phase 2 and 3 trials that include older individuals and those at high risk of infection for the efficacy, safety, and immunogenicity of ChAdOx1 NCoV-19 given at a single or two-dosages in the United Kingdom, Brazil, and South Africa. Once they have enough data with adults, they will set up a study with children too.

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