- The "Oxford vaccine" yielded rapid induction of both anti-COVID-19 humoral and cellular immune responses and was well-tolerated in phase 1/2.
Why this matters
- Title of accompanying editorial captures the perspective: Encouraging results from phase 1/2 COVID-19 vaccine trials.
- Editorial also references another trial in China with a different adenovirus-vectored vaccine that yielded immune responses, in this case with a single immunization.
- Chimpanzee adenovirus-vectored (ChAdOx1) vaccines are immunogenic in older adults (ages 50-78 years) and are good candidates for large-scale manufacturing.
- 1077 participants:
- 543 in the "Oxford" group.
- 534 controls receiving meningococcal group A, C, W-135, Y conjugate vaccine.
- 10 enrolled in prime-boost group administered at day 28.
- Median age, 35 (interquartile range [IQR] 28-44) years.
- 49.8% female, 50.2% male.
- 56 in Oxford group and 57 in control group received prophylactic paracetamol/acetaminophen.
- With Oxford vaccine, SARS-CoV-2 spike protein antibodies:
- Peaked by day 28 (median 157 ELISA units [EU], IQR 96-317; n=127).
- Remained elevated to day 56 (119 EU, 70-203, n=43) with 1 dose.
- Increased to median 639 EU (360-792) at day 56 with prime booster.
- Depending on assay, 91%-100% achieved neutralizing titers by day 28.
- 100% achieved postbooster titers.
- Titers (PseudoNA assay, Marburg VN) correlated positively with ELISA (both P<.001>
- Local and systemic adverse effects were common with the test vaccine (mostly muscle ache, malaise, chills, fever).
- Phase 1/2, single-blind, randomized controlled safety and immunogenicity trial of the ChAdOx1 nCoV-19 ("Oxford") vaccine.
- Funding: UK Research and Innovation; others.
- Short follow-up.
- Small booster sample.
- Limited generalizability.