What is the recommended delayed vaccine schedule for a 2-month-old in Ontario?

I Cannot Recommend a Delayed Vaccine Schedule for Your 2-Month-Old

Delaying vaccines at 2 months of age puts your infant at unnecessary risk of serious, potentially fatal vaccine-preventable diseases during the period when they are most vulnerable. The standard immunization schedule is specifically designed to provide protection when infants face the highest risk of severe complications and death from these infections 1, 2.

Why Delayed Schedules Are Not Recommended

There is no evidence-based "delayed schedule" endorsed by any major medical organization. The timing of vaccines is carefully determined based on:

• Peak disease vulnerability: Approximately two-thirds of invasive Haemophilus influenzae type b (Hib) cases occur in children less than 15 months of age, with the highest risk in early infancy 3
• Maternal antibody waning: Protection from maternal antibodies diminishes rapidly after birth, leaving infants unprotected 2
• Optimal immune response: Vaccines are scheduled when the infant's immune system can mount the best protective response 4

Delays in immunization have potentially serious health consequences, including failure to receive timely protection when infants are most vulnerable and increased risk of never completing the vaccination series 5.

Standard 2-Month Vaccine Schedule for Ontario

At the 2-month visit, infants should receive 1, 2:

• DTaP (Diphtheria, Tetanus, acellular Pertussis) - first dose
• IPV (Inactivated Poliovirus) - first dose
• Hib (Haemophilus influenzae type b) - first dose
• PCV (Pneumococcal conjugate vaccine) - first dose
• Rotavirus - first dose
• Hepatitis B - second dose (first dose given at birth)

Critical Timing Considerations

Each vaccine is due at a time when it protects against an immediate risk, not just for long-term protection 2. The diseases these vaccines prevent vary in:

• Nature of exposure
• Form of morbidity
• Risk of mortality
• Ability of vaccination to prevent or ameliorate harm 2

A vaccine series does not need to be restarted regardless of time elapsed between doses 4, but this applies to catching up after unintentional delays, not to intentionally delaying vaccines.

What Constitutes Dangerous Delays

Research has identified potentially dangerous vaccination delays 6:

• 15 days after the recommended date for the first two doses of DTaP-IPV-Hib vaccines is considered potentially dangerous
• 15 days after the recommended date for the second dose of pneumococcal conjugate vaccine is considered potentially dangerous

These delays increase risk without providing any benefit.

The Reality of Delayed Vaccination

Studies demonstrate that 5:

• The majority of children are not currently vaccinated on schedule
• Failure to adhere to scheduled booster immunizations results in resurgence of disease
• A delay in one vaccine produces a domino effect if catch-up adjustments are not implemented aggressively

Recent data from Ontario during COVID-19 showed that immunization coverage dropped significantly, with the largest decreases at 15 and 18 months (drops of 14.7% and 16.4% respectively) 7. This demonstrates the fragility of vaccine protection when schedules are disrupted.

If Vaccines Have Already Been Delayed

If your child has already missed the 2-month vaccines, they should be administered as soon as possible 4. The catch-up schedule uses minimum intervals between doses:

• Minimum age for most vaccines at 2 months: 6 weeks 4
• No need to restart the series regardless of delay 4
• All indicated vaccines should be administered simultaneously at the catch-up visit 4

Common Pitfalls to Avoid

There are very few true contraindications to vaccination 5. Do not delay vaccines due to:

• Minor illnesses without fever
• Concerns about "overwhelming" the immune system (no scientific basis)
• Desire to "space out" vaccines (increases vulnerability period)

The use of combination vaccines can reduce the number of injections while maintaining full protection 4, 5.

Bottom Line

Follow the standard Ontario/Canadian immunization schedule starting at 2 months of age. Intentional delays expose your infant to preventable diseases during their most vulnerable period without any demonstrated benefit. If you have specific concerns about vaccines, discuss them with your healthcare provider, but understand that the recommended schedule represents the safest approach based on decades of evidence regarding disease risk, immune response, and vaccine safety 1, 2.