Travel Medicine and Vaccines: FAQ from the Drug and Poison Information Centre

Updated on July 16, 2021 (Originally posted on February 3, 2020) The Tablet

Answers to Frequently Asked Questions from the Drug and Poison Information Centre

By Aly Karamali, RPh and Shelina Rayani, RPh, CSPI, BC Drug and Poison Information Centre
Reviewed by Dr Roy Purssell, MD, FRCPC and Hanif Rayani, RPh


Q: Can all travel vaccines be administered at the same time?

A: Taking into account site restrictions for parenteral vaccines and patient tolerance, there is no limit to the number of vaccines that can be administered on the same day

  • Inactive vaccines can be administered at the same time, or any time before/after other inactive or live vaccines
  • Live parenteral vaccines can be administered together on the same day. If two live parenteral vaccines are not administered on the same day, they should be spaced at least 4 weeks apart
  • Live oral or intranasal vaccines can be administered at the same time, or any time before/after other live or inactive vaccines, regardless of route. Note: Oral cholera (inactive) and oral typhoid (live) are exceptions and should be spaced 8 hours apart


Q: Can different hepatitis A or hepatitis B vaccines be used interchangeably to complete 
immunization series?


  • Any age appropriate single entity hepatitis A vaccine (e.g. Avaxim, Havrix) can be used interchangeably to complete a hepatitis A series following the Canadian Immunization Guideline schedule
  • Any age appropriate single entity hepatitis B vaccine (e.g. Engerix, Recombivax) can be used interchangeably to complete a hepatitis B series following the Canadian Immunization Guideline schedule
  • If a combination hepatitis A and B vaccine is required to complete a series started with a single entity product:
    • Complete the hepatitis A series by administering 2 additional doses of the combination vaccine 6 months apart
    • Complete the hepatitis B series by administering 2 additional doses of the combination vaccine following the 0, 1, 6 month regimen

Q: Is there a minimum interval required between Td (tetanus-diptheria) and Tdap (tetanus-diptheria-pertussis) vaccinations?

A: No minimum interval between Td and Tdap when Tdap is given for pertussis protection


Q: Do interruptions or delays in a vaccination series require the series to be restarted?


  • In general, interruption of a multi-dose vaccine series does not require restarting the series as the final antibody concentration would not be affected
  • An exception to this rule is the oral typhoid vaccine which needs to be restarted if there is a longer interval (more than 1 week) between doses

Q: Is malaria prophylaxis required in those who previously lived in malaria endemic areas or have had a malaria infection?


  • Previous malaria infection does not confer long term immunity. Natural acquired immunity to malaria is lost once an individual moves away and lives in a non-malaria endemic country for a period of 6 months or longer
  • An individual revisiting a malaria endemic country is susceptible to malaria and chemical prophylaxis is required

Q: Is there a “travel checklist” for patients who are planning on travelling?

A: A comprehensive checklist for travellers can be located at the CDC website (USA)


Q: What are the most current guidelines for traveller’s diarrhea?

A: Guidelines were developed and published in a 2017 supplement to the Journal of Travel Medicine. These are summarized in the Canadian Pharmacists Journal and available at the following link:

Guidelines review: 

  • Classification of traveller’s diarrhea as mild, moderate, severe and persistent
  • Prophylaxis not routinely indicated; it may be considered for certain populations (e.g. immunocompromised, chronic illness)
  • Antibiotic of choice (based on global resistance patterns) indicated for treatment of moderate to severe cases and diarrhea with presence of blood
  • Loperamide indicated for treatment of mild, moderate or severe cases. NOT to be used for management of diarrhea with presence of blood
  • Bismuth Subsalicylate indicated for treatment of mild cases and for prophylaxis when indicated
  • What are current recommendations for treatment of traveller’s diarrhea in children?
  • Oral rehydration salts, bland diet, supportive care
  • Loperamide contraindicated in <2yrs age. Some references do not recommend for <3yrs as it has been reported to cause sedation, respiratory depression and paralytic ileus
  • Bismuth Subsalicylate indicated for >12yrs: 524mg qid. Concern: potential for salicylate toxicity, Reye’s Syndrome
  • Bismuth subsalicylate: 262 mg (in 15 mL of liquid Pepto Bismol® or one tablet) is approximately equivalent to 131 mg ASA


Q: Is DUKORAL® recommended for prevention of traveller’s diarrhea in Canada?


  • DUKORAL® is an inactive oral vaccine indicated for the prevention of cholera caused by V. cholerae and for traveller’s diarrhea caused by enterotoxigenic E. coli (ETEC)
  • Due to limited evidence demonstrating benefit, Committee to Advise on Tropical Medicine and Travel (CATMAT) does not routinely recommended DUKORAL® for the prevention of traveller’s diarrhea
  • Certain travellers at risk of complications (e.g. immunosuppressed, cannot risk period of illness during travel) may still consider DUKORAL® prior to travel

Q: If a dose of DUKORAL® is taken without mixing in the bicarbonate buffer powder, is the dose still effective?


  • The vaccine component is acid labile. The bicarbonate buffer protects vaccine from gastric acid
  • If administered without the buffer, vaccine efficacy may be impacted and dose should be readministered


Q: Any additional resources for vaccine-related questions?


  • BCCDC Immunization Manual
  • Canadian Immunization Manual
  • Public Health Unit Immunization Nurse

Disclaimer: FAQs derived from travel-related questions received at the BC DPIC Information Line. It does not address all travel-related vaccine information. The responses are not comprehensive due to article space restrictions. It is encouraged to review specific vaccine information further.



1.  Ask the Experts [Internet]. Immunization Action Coalition. Updated 2019 July 23. Available from:

2.  Canadian Immunization Guide [Internet]. Government of Canada. Updated 2018 Jan 24. Available from:

3.  Dukoral monograph [Internet]. Valneva 2015. Accessed from Drug Product Database at

4.  BC Immunization Manual [Internet]. BC Centre for Disease Control. Updated 2019 Oct. Available from:

5.  Ahmed T, Bhuiyan TR, et al. Vaccines for preventing enterotoxigenic Escherichia coli (ETEC) diarrhoea. Cochrane Database Syst Rev 7:CD009029. doi:10.1002/14651858.CD009029.pub2.

6.  Statement on Travellers' Diarrhea [Internet]. An Advisory Committee Statement (ACS) Committee to Advise on Tropical Medicine and Travel (CATMAT). Government of Canada. Updated 2015 May 1. Available from:

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8.  International travel and health: situation as on 1 January 2009. Geneva: World Health Organization; 2009. pg 150

9.  Arguin PM, Tan KR. CDC Yellow Book Chapter 3: Malaria. [Internet]. 2017 June 12. Available from:

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13.  Mark S. Riddle, Bradley A. Connor, Nicholas J. Beeching et al.  Guidelines for the prevention and treatment of travelers’ diarrhea: a graded expert panel report, Journal of Travel Medicine, Volume 24, Issue suppl_1, 1 April 2017, Pages S63–S80,

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17. BCCH Formulary

18.  Ashkenazi S, Schwartz E, O’Ryan M.  Travelers’ Diarrhea in Children.  What Have We Learnt?  Pediatr. Infect. Dis. J.  2016  Jun; 35(6): 698-700.

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21. Anderson IB.  LOMOTIL AND OTHER ANTIDIARRHEALS.  In:  Olson K, editor.   Poisoning & Drug Overdose.  6th ed.  New York:  McGraw-Hill;  2012. P. 262-63.

22. Hagmann SHF, Christenson JC, Fischer PR.  Travelers’ diarrhea in children: a blind spot in the expert panel guidelines on prevention and treatment.  J Travel Med 2018 Jan 1; 25(1). DOI: 10.1093/jtm/tax075

23. Pepto Bismol [Internet] [cited 2020 Jan 21].  Available from:

24. Goldman RD.  Bismuth salicylate for diarrhea in children.  Can Fam Physician. 2013 Aug; 59(8): 843-844.

25. Lewis TV, Badillo R, Schaeffer S, et al.  Salicylate toxicity associated with administration of Percy medicine in an infant.  Pharmacotherapy.  2006 Mar; 26(3): 403-9

26. Kent D, editor.  Poison Management Manual.  Vancouver: BC Drug and Poison Information Centre;  2015 March.  Salicylates.

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