Based on the information provided about your 19-month-old child having a fever with no other symptoms and the fact they are teething, it may be a good idea to consult a healthcare professional and potentially get them tested for COVID-19. It is recommended to monitor the fever and consider getting tested if it persists or if there is a risk of exposure to the virus. It is also mentioned that teething can sometimes cause a slight increase in body temperature, but with a high fever like the one described, it is better to err on the side of caution and seek medical advice.