ABSTRACT
Background: Adults and childrenwith cancer are susceptible to severe SARS-CoV-2 disease. Vaccination is protective;data beyond initial response and regarding effect of booster doses are lacking in cancer patients. Method(s): The SerOzNET study assesses SARS-CoV-2 vaccine response in haematological and solid cancer patients aged 5 and older. Patients are recruited pre dose 1 and receive standard BNT162b2 (Pfizer) or ChadOx1-S (AstraZeneca) vaccine. Blood is taken at baseline and after each dose. Neutralizing antibody (NAb) titre, absolute antibody titre (Abbott), T cell response (IFN-gamma) and epigenetics are analysed. Clinical data are collected. Patients are followed for up to 3 months beyond dose 5. Result(s): 105 children (64% haem, 36% solid cancers) and 399 adults (35% haem, 65% solid cancers) were enrolled. In adults, NAb response rate increased after dose 3 (Post 2: 40% haem, 87%solid;Post 3:70%haem,97%solid). Post dose 2, predictors of nonresponse were ChadOx1-S vaccine (OR 3 p = .02), haem cancer (OR 14 p < .001), ECOG >=1 (OR 2.6 p = .01) and steroids (OR 5 p = .01). Post dose 3, only haem cancer predicted non-response (OR 16). IFN-gamma response is available for a subset, detectable in 41/90 (46%) postdose 1, 78/96 (81%) post-dose 2 and 35/42 (83%) post-dose 3;without significant difference between haem and solid cancer. In children, NAb response post dose 2 is available for 50 patients. Response rate between haem (19/31, 61%) and solid patients (13/19, 68%) was similar. IFN-gamma response post dose 2 was also similar: (14/22, 63%) vs solid patients (12/14, 85%) (p = .25). Analysis is ongoing. Conclusion(s): Response to two doses of SARS-CoV-2 vaccine is suboptimal in patients with cancer. The third priming dose is integral, with significantly higher response rates observed. 36% of children did not develop neutralizing antibodies post dose 2;subsequent doses are likely to be important for young patients.