New York, May 17 : Patients with cancer whose immune systems are being supported or rebuilt by bone marrow transplantation should begin receiving vaccines for protection against SARS-CoV-2 three months post-transplant, according to a new study. People with cancer, and especially those undergoing bone marrow transplantation as part of their treatment, are highly vulnerable to infection. Initial studies showed that up to 30 per cent of these patients who became infected with the virus that causes Covid-19 died within four to six weeks, said researchers. The findings, published in The Lancet journal eClinicalMedicine, showed that SARS-CoV-2 antibody titers, neutralising antibody titers and T-cell receptors (TCR) data did not significantly differ at the tested time points following the second vaccination, whether patients started vaccinations before four months or during the period of four to 12 months after bone marrow transplant. Results did not appear to be impacted by the use of immunosuppressive medications or a diagnosis of graft versus host disease. "We undertook this study to help patients and their doctors determine the best time to begin SARS-CoV-2 vaccination because there was little information on these vaccines in this group of patients," said lead author Dr. Joshua Hill, Associate Professor of medicine at University of Washington School of Medicine. "We found that initiating an mRNA vaccination series between three to four months after bone marrow transplant should be routinely performed as part of a comprehensive infection prevention strategy," added Dr Hill, who is also a specialist at Fred Hutchinson Cancer Center. Although current guidelines in the US call for SARS-CoV-2 vaccination to start three to six months post-transplant, those recommendations were based on limited evidence, such as historical experience with previous vaccines that targeted other pathogens and did not use the mRNA platform. Further, the Covid-19 vaccine efficacy clinical trials did not include participants who had undergone bone marrow transplantation, the researchers said. The study, published in The Lancet journal eClinicalMedicine, tracked immune responses and safety data in 175 patients who received a first mRNA vaccination within 12 months of bone marrow transplant. All but one patient received mRNA-based vaccines. Of the total, 76 participants were vaccinated within the first four months following bone marrow transplantation; 99 participants were vaccinated between four and 12 months of the procedure. aceOur study provides encouraging proof-of-concept for using early vaccination to target this and other pathogens using the mRNA platform," Hill said. /IANS