Our study aimed to explore immunization status in CP patients and examine whether there is an association between demographic, medical, and receipt of the vaccines which are included in NIP. To the best of our knowledge, the present multicenter study is the first in the English literature to investigate the immunization status of the CP population. Our results showed that the vaccination rate of children with CP for vaccines included in the Ministry of Health’s NIP was lower than healthy children. These findings are similar to a Canadian study (9) that examined vaccination status in children with physical disabilities and included 57 children with CP. Their results showed lower than expected rates of vaccination (63%). The study results from Australia were found more remarkable, and the 'up-to-date' vaccination rate was demonstrated to be 19.2% in CP patients (10). In contrast, a study from Turkey (5), showed no significant difference between immunization rates of children with chronic neurologic diseases versus the healthy population. This study put forth the vaccination rate in 95.6% of patients with chronic neurologic diseases received age-appropriate vaccination according to the Ministry of Health’s NIP. In our study, it was noticed that the administration rates were higher in vaccines that were included in the NIP previously (e.g., hepatitis B, BCG, OPV, MMR, DTaP-IPV-Hib), and lower in those added lastly (e.g., PCV, varicella, hepatitis A). This was attributed to the fact that nearly half of the patients presented in our study were born before vaccines were included in the NIP. MMR and DTaP-IPV-Hib vaccines, which are the other components of childhood vaccinations, have been found less completed with a rate of 77.3% and 60.5% respectively in this group than the vaccines included in the NIS for a long time. Similarly, Greenwood et al. evaluated the vaccination status of patients with CP, and the MMR vaccine was reported to be the most missed vaccine followed by DTaP -Hib, and OPV (10).
The patients with CP have a higher risk of morbidity and mortality than the healthy population for vaccine-preventable diseases. Respiratory diseases are the most frequently reported cause of morbidity and mortality in CP, hence, by ameliorating respiratory status, quality of life, and life expectancy might be augmented. All studies of CP mortality investigating cause attribute more than half of the observed deaths to respiratory diseases (11). It is important to implement pneumococcal and influenza vaccines that cause pneumonia not to aggravate respiratory problems, which are the cause of almost half of the deaths. As with typically developing children, children with CP should be vaccinated per the currently used vaccination schedule. The rate of complete vaccination with PCV, which is recommended for all Turkish children, was lower in our study than in the general population, among which it is reported to exceed 95% after 2008 (12). Because of the recent implementation of the PCV, most of the older children born in Turkey before 2008 had not received it as a generally administered vaccine-like our patients. The most common cause associated with required hospitalization was pneumonia, with a rate of 52%, in the last year in our study population. It was noted that the rate of none/incomplete vaccination was higher in those hospitalized patients for pneumonia. Also, it was found that not only the pneumococcal vaccine but also BCG, OPV, and MMR vaccines were implemented at a lower rate in this group. Another remarkable result was that influenza vaccination was recommended for patients hospitalized due to pneumonia at a higher rate, and patients were administered influenza vaccine more common. This may be because preventive implementation and vaccines are considered more frequently during follow-up in patients hospitalized due to pneumonia.
Advisory Committee on Immunization Practices recommended influenza vaccine for people with chronic pulmonary, cardiovascular, renal, hepatic, neurological, hematological, metabolic diseases or immunocompromised people in their recommendations for 2020–2021 Control of Seasonal Influenza with Vaccines (13). In a cohort study by Keren et al., 322 of 745 patients with laboratory-confirmed influenza, had one or more chronic diseases. Neurological and neuromuscular diseases are independent risk factors for respiratory failure (14). In another study of 830 pediatric deaths associated with laboratory-confirmed influenza reported to the Center of Disease Control between October 2004 and September 2012, an underlying neurological disease was found at a rate of 33% (15). In the meta-analysis by Gill et al. in 2014, in 27 studies involving 14086 patients, neurological diseases were accepted as a high-risk factor for influenza-related hospitalizations (16). In a study by Pandolfi et al., among 275 patients with chronic diseases, the lowest vaccination rate for influenza vaccine was found in patients with a neurological disease with 25% (17). Considering that the frequency of influenza vaccination is generally low in our country, it is low in patients with CP, who are in the risk group. In our study, only 3.4% of the patients with CP were vaccinated against influenza throughout their lives. Similarly, only 2.6% of the patients were vaccinated during the season of the study. In a study from our country, Dinleyici et al. evaluated the vaccination of 366 patients with chronic neurological disease and found that 86.6% of patients had never been vaccinated against influenza in their life (5). Although it is not as rare as in our country, there are examples of missing vaccination opportunities for these patients in other countries in the literature. In a study from the US, Havers et al. evaluated the vaccination records of 184460 patients with ≥ 1 neurological disease(s) between 2006 and 2014. They found that even in the 2013–2014 season when vaccination was the highest, less than half of the patients and 1/3 of these in the 10–17 years age group were vaccinated against influenza (18). Worldwide, we need to develop interventions to increase the vaccination rates of the patients with CP who are in the risk group for influenza complications.
CP develops in the fetal or infant brain causing activity restriction and is not progressive. It is a group of diseases that affects movement and posture (19). In a study conducted by Serdaroğlu et al. with 41861 children aged between 2–16 years in our country, the prevalence of CP was reported as 4.4 per 1000 live births (20). Patients may encounter many problems commonly seen in this disease, e.g., intellectual disability, behavioral disorders, epilepsy, somatosensation disability, visual and auditory disorders, orthopedic deformities, gastrointestinal and nutritional problems. The most common concomitant diseases were epilepsy, orthopedic problems, and growth retardation in our study population. More than half of patients who present to our study have severe motor dysfunction, which makes it difficult to move. Children with CP who had higher levels of motor dysfunction (level 4 and 5) were more likely to be overdue immunizations. A study from Canada (9) showed that children with moderate to severe disabilities are less likely than those with a mild disability to have received a basic series of immunizations. Similarities in this study and those observed associations between severe motor dysfunction and vaccination prompted us to investigate the potential role of the immunization status of this disease. In our study, the vaccination rate of hepatitis B, BCG, DTaP-IPV-Hib, OPV, and MMR was statistically significantly lower in patients with severe motor dysfunction. The clinical picture of the association between low vaccination rate and severe motor dysfunction is most likely a result of a complex interplay between direct and indirect effects of CP. It may be that this group of children have an ongoing severe chronic illness resulting in frequent hospitalizations delaying age-appropriate immunizations or that the high level of care required may limit the time available for immunization appointments. Or, vaccines may have been neglected because the physicians who follow patients are concerned with other medical problems. Despite our results, Greenwood et al. demonstrated no association with motor dysfunction level and vaccination rate (10). They discussed that the results may have been influenced by survival bias as most children who died were severe motor dysfunction, and the immunization records for these children had been removed from their national database.
Barriers to vaccination of patients with CP are familial factors and false contraindications of both parents and healthcare professionals. The most important reason for incomplete vaccination in our study was due to primary school vaccination in children. Therefore, we think that the administration of primary school vaccinations from primary care physicians and the development of a catch-up vaccination schedule for those patients without an age-appropriate vaccination will be of great benefit in protecting against diseases and increasing the quality of life in children with CP. One study concluded that some parents may be concerned that the possible adverse outcomes of immunizations may outweigh the potential benefits, such as increasing frequency of seizures and a small proportion of parents may believe that immunizations contributed or caused their child’s disability (10). These concerns were rarely mentioned by the parents of our patients.