Until now, only injectable vaccines against influenza have been available. They have been used primarily by older adults, who are at risk for complications from influenza. A new vaccine administered in a nasal spray has proven effective in preventing influenza in children. Since children are significantly more likely than adults to contract and spread influenza, making the new vaccine widely available for children will greatly reduce the spread of influenza across the population.

Which of the following, if true, most strengthens the argument?

【选项】If a person receives both the injectable and the nasal-spray vaccine, the two vaccines do not interfere with each other.