Flu Vaccine Safety Studies

Flu Vaccine and COVID-19


Influenza Vaccine Does Not Increase the Risk of Coronavirus or Other Non-influenza Respiratory Viruses: Retrospective Analysis From Canada, 2010–2011 to 2016–2017.

In Canada a study reviewing influenza vaccine effectiveness for 7 years -2010–2011 to 2016–2017 influenza seasons - showed having influenza vaccine did Not increase the risk of Coronavirus or other non-influenza respiratory viruses including coronaviruses.

Skowronski et al

Clinical Infectious Diseases, ciaa626, https://doi.org/10.1093/cid/ciaa626  (you will be directed to the Oxford University website) 

Published:  22 May 2020



Influenza Vaccination Is Not Associated With Detection of Noninfluenza Respiratory Viruses in Seasonal Studies of Influenza Vaccine Effectiveness 

This US  study over 5 years of flu seasons showed significant vaccine effectiveness and no evidence that flu vaccination, including  live attenuated influenza vaccine (LAIV),  is associated with an increased risk of infection with non-influenza respiratory viruses including coronaviruses.

Sundaram et al.

Clinical Infectious Diseases, Volume 57, Issue 6, 15 September 2013, Pages 789–793, https://doi.org/10.1093/cid/cit379 (you will be directed to the Oxford University website) 


Safety of Live Attenuated Influenza Vaccine


Evaluation of the safety of live attenuated influenza vaccine (LAIV) in children and adolescents with asthma and high-risk conditions: a population-based prospective cohort study conducted in England with the Clinical Practice Research Datalink

This study did not identify any new safety concerns associated with the administration of live attenuated influenza vaccine (LAIV) in 11463 children and adolescents with high-risk medical conditions, when used as a trivalent formulation during the 2013–2014 season or as a quadrivalent formulation during the 2014–2015 season in the UK.

Caspard H et al

BMJ Open 2018 Dec 9; 8(12):e023118.doi: 10.1136/bmjopen-2018-023118. https://pubmed.ncbi.nlm.nih.gov/30530581/ (you will be directed to the Pubmed website) 



The safety of live attenuated influenza vaccine in children and adolescents -2 through 17 years of age: A Vaccine Safety Datalink study

In a study of trivalent LAIV safety in a large cohort of 396,173 children, few serious adverse events were detected. Rarely, anaphylaxis and syncope (fainting) occurred following LAIV. These data provide reassurance regarding continued LAIV use.

Daly M et al.

Pharmacoepidemiol Drug Saf. 2018 Jan; 27(1): 59–68



Safety of quadrivalent live attenuated influenza vaccine in subjects aged 2-49 years

In this large population (62040) study of individuals aged 2-49 years, no safety signals associated with the administration of Q/LAIV were observed.

Baxter R

Vaccine 2017 Mar 1; 35(9):1254-1258 doi: 10.1016/j.vaccine.2017.01.062. https://pubmed.ncbi.nlm.nih.gov/28162825/ (you will be directed to the Pubmed website) 



Vaccinating high-risk children with the intranasal live-attenuated influenza vaccine: the Quebec experience

Results from randomized controlled trials in healthy children and in asthmatics have demonstrated superior efficacy of LAIV over the injectable inactivated influenza vaccine (IIV). LAIV is well tolerated: its administration is associated with runny nose and nasal congestion, but not with asthma exacerbations, and it is well tolerated in children with cystic fibrosis, when compared to inactivated influenza vaccine. The vaccine is well accepted by children and parents and can be included in clinics targeting children with chronic, high-risk conditions, not leading to immunosuppression 

Caroline Quach

Paediatr Respir Rev 2014 Dec;15 (4):340-7. doi: 10.1016/j.prrv.2014.06.002 https://pubmed.ncbi.nlm.nih.gov/25242731/ (you will be directed to the Pubmed website) 



Shedding and immunogenicity of live attenuated influenza vaccine virus in subjects 5-49 years of age

This is the first study to comprehensively evaluate nasal shedding of LAIV in individuals 5-49 years of age. Shedding was generally of short duration and at low titers. Study findings support the current recommendation of the US Advisory Committee on Immunization Practices that LAIV recipients should only avoid contact with severely immunosuppressed persons (e.g., hematopoietic stem cell transplant recipients) for 7 days after vaccination. The risk of transfer of virus to a susceptible person such as someone with severe immunosuppression is theoretical.

Block S et al.

Vaccine. 2008 Sep 8; 26(38):4940-6.  doi: 10.1016/j.vaccine.2008.07.013 https://pubmed.ncbi.nlm.nih.gov/18662737/ (you will be directed to the Pubmed website) 


Flu Myths: Dispelling the Myths Associated With Live Attenuated Influenza Vaccine

Live attenuated influenza vaccine is a safe, highly immunogenic, and effective vaccine. It is well tolerated; only mild and transient upper respiratory infection symptoms occur with LAIV vaccine, even in higher-risk patients with asthma or the early stages of human immunodeficiency virus in certain populations, LAIV is as effective as, and in some cases more effective than, inactivated influenza in preventing influenza infection. Although shedding of vaccine virus is common, transmission of weakened (attenuated0a vaccine virus has been documented only in a single person, who remained asymptomatic. In the age groups for which it is indicated, LAIV is a safe and effective vaccine to prevent influenza infection

Tosh P K et al.

Mayo Clin Proc. • January 2008; 83(1):77-84 https://www.mayoclinicproceedings.org/article/S0025-6196(11)61121-X/pdf (you will be directed to the Mayo Clinic website) 



A randomized, double-blind study of the safety, transmissibility and phenotypic and genotypic stability of cold-adapted influenza virus vaccine

One hundred ninety-seven healthy children aged 9 to 36 months attending day care were randomized to receive vaccine or placebo vaccine. Post-vaccination viral shedding, safety, genotype and phenotype of shed viruses and probability of transmission were assessed.

Shedding of the weakened (attenuated) vaccine virus occurred in young children in a day care setting but no illness occurred among children who received the vaccine or placebo or in the only child to whom the weakened (attenuated) vaccine virus was transmitted.

Vesikari et al

Pediatr Infect Dis J 2006 Jul; 25(7):590-5 https://pubmed.ncbi.nlm.nih.gov/16804427/ (you will be directed to the Pubmed website) 


This page was added on 14 September 2021